The device description is Section 1 of MDR Annex II and the first thing an auditor reads. Under Regulation (EU) 2017/745, Annex II Section 1, it must identify the device and its variants, state the intended purpose as defined in Article 2(12), describe the principles of operation, list materials and key functional elements, cite the classification rule from Annex VIII, and reference any previous generations and similar devices on the market. Write it once, write it precisely, and write it in a shape that survives design changes — because every other section of the technical file inherits its scope from this one.

By Tibor Zechmeister and Felix Lenhard. Last updated 10 April 2026.

TL;DR

  • The device description is the first numbered section of MDR Annex II. It is the scope-setter for the entire technical file.
  • Annex II Section 1 prescribes the content: identification of the device and variants, intended purpose, intended users and patient populations, indications and contraindications, principles of operation, materials, key functional elements, classification rationale under Annex VIII, and a description of previous generations and similar devices on the market.
  • The intended purpose belongs here and nowhere else as the source of truth. Every other section of the file — labelling, GSPR checklist, risk file, clinical evaluation — inherits it. Under Article 2(12) of Regulation (EU) 2017/745, the intended purpose is the use for which the device is intended according to the data supplied by the manufacturer on the label, in the instructions for use, or in promotional or sales materials. Everything the manufacturer says about the device is in scope.
  • The most common mistake is treating Section 1 as a marketing blurb. It is a technical specification with legal weight.
  • A well-written device description survives design changes. A sloppy one has to be rewritten every time something about the product moves.

Why Section 1 is the hinge of the whole file

Open any technical file that has been through a Notified Body audit and the first section the auditor reads is the device description. This is not a formality. The device description sets the scope for every downstream section. It tells the auditor what is being assessed, against which intended purpose, under which classification rule, and in which variants. Every sentence in Section 4 (GSPR), Section 5 (benefit-risk and risk management), and Section 6 (verification and validation) is implicitly bounded by what Section 1 says the device is.

If Section 1 is wrong, everything downstream is wrong. A classification rule cited incorrectly in Section 1 contaminates the conformity assessment route. An intended purpose drafted loosely in Section 1 leaves the clinical evaluation unable to match its evidence to its claims. A variant omitted from Section 1 produces a device on the market that the file does not cover. These are not theoretical errors. Each one becomes a finding, and several of them become the kind of finding that delays a certificate.

The pillar post on technical documentation under MDR makes the broader point that structure beats volume. Section 1 is the section where that principle has the highest leverage. A three-page device description that is tight, precise, and version-stable is worth more than a fifteen-page one that drifts with every design review.

What Annex II Section 1 requires

Annex II Section 1 of Regulation (EU) 2017/745 specifies the content of the device description and specification, including variants and accessories. The required content:

  • Device identification. Product or trade name, general description, intended purpose, intended users where appropriate, and the patient populations intended to be diagnosed, treated, or monitored.
  • The UDI-DI (Basic UDI-DI) assigned to the device, once available.
  • Intended users and use environment. Who operates the device, in which clinical or home setting, under what level of training.
  • Principles of operation. How the device achieves its intended purpose — mechanism of action for physical devices, algorithmic principle for software, and so on. A non-specialist with technical literacy should be able to read this and understand how the device works.
  • The rationale for qualification as a medical device. Why this product meets the definition of a medical device in Article 2(1) of Regulation (EU) 2017/745 — the intended medical purpose and how the principal intended action is achieved.
  • The risk class and the justification for the classification rule applied under Annex VIII. Not just "Class IIa" — the specific rule number, the reasoning that led to it, and the factors considered (invasiveness, duration of contact, active versus non-active, software function, and so on).
  • An explanation of any novel features of the device. If the device uses a technology, material, or principle that is new to the market, this is where it gets flagged.
  • A description and specification of variants and accessories intended to be covered by the same technical documentation. Which variants exist, what differs between them, and why the same conformity argument covers the whole family.
  • A general description of the key functional elements — the parts, components, composition, or software modules that perform the medical function — often supported by images, diagrams, or a block diagram.
  • A description of the raw materials incorporated into key functional elements and those making direct contact with the human body or indirect contact (for example, through extracorporeal circulation of body fluids).
  • Technical specifications — features, dimensions, performance attributes, and characteristics that make the device what it is.
  • A reference to previous and similar generations of the device. Any earlier generation placed on the market by the manufacturer, and any similar device available on the EU or international market, identified at a level sufficient to understand the lineage.

This is a lot of content for one section, and it is all required by the Regulation. Section 1 is not a place to be brief for the sake of brevity. It is a place to be precise and complete, and nothing more.

Device description versus intended purpose — the distinction that trips teams up

Two related concepts live inside Section 1, and startups routinely collapse them into one paragraph when they should be kept distinct.

The device description is the technical answer to "what is this thing?" Materials, components, architecture, dimensions, principle of operation. It describes the physical (or digital) object.

The intended purpose is the legal answer to "what is this thing for?" Under Article 2(12) of Regulation (EU) 2017/745, the intended purpose is the use for which a device is intended according to the data supplied by the manufacturer on the label, in the instructions for use, or in promotional or sales materials or statements, and as specified by the manufacturer in the clinical evaluation. The scope of the intended purpose is set by what the manufacturer communicates, not by what the device could hypothetically do.

Two consequences follow from the Article 2(12) wording. First, anything the company says publicly about the device — on the website, in the pitch deck, in a conference talk — is part of the intended purpose. If the marketing claim exceeds the technical file, the file is out of scope with its own stated intended purpose. Second, the classification rule, the clinical evaluation scope, and the benefit-risk analysis all trace back to the intended purpose as written in Section 1. If Section 1 says the device diagnoses condition X in adult patients in hospital settings, the clinical evaluation must provide evidence for X, in adults, in hospital. A slightly different clinical evaluation scope is a structural finding.

Write the device description and the intended purpose as two adjacent, clearly labelled sub-sections. Do not merge them. Do not paraphrase the intended purpose in the device description narrative. The intended purpose is a reference text that every other section of the file quotes — it needs to be quotable.

The post on documenting intended purpose in the technical file goes deeper on the exact wording discipline.

What to include in Section 1 — and what to leave for later sections

Section 1 carries more weight than teams expect, and the temptation is to pour everything into it. This is a mistake. Section 1 is the scope-setter, not the evidence container. The evidence belongs in the sections that Annex II reserves for it.

Include in Section 1:

  • The identification, intended purpose, classification rationale, principles of operation, materials list, and variant family — the facts that the rest of the file depends on.
  • A crisp description of how the device works, at a level a technically literate reader can follow.
  • The specific Annex VIII rule citation and the reasoning that led to it.
  • Diagrams or images that communicate structure efficiently. A single labelled diagram beats three paragraphs of prose.

Leave for later sections:

  • Label text, IFU content, and packaging specifications. These belong in Section 2 (information supplied by the manufacturer). Section 1 references them; it does not reproduce them.
  • Manufacturing process descriptions, supplier lists, and site identification. These belong in Section 3. Section 1 describes the device, not how it is built.
  • Evidence of conformity to Annex I GSPR. This belongs in Section 4. Section 1 cites the classification rule; it does not argue conformity.
  • The risk management file and benefit-risk analysis. These belong in Section 5. Section 1 defines the intended purpose that the benefit-risk analysis then weighs against the risks.
  • Test reports, verification and validation evidence, and clinical evaluation. These belong in Section 6. Section 1 states the claims that Section 6 then substantiates.

Keeping Section 1 scoped to its own job shortens it, sharpens it, and stops the document drift that happens when evidence and scope are mingled in the same paragraphs.

Common gaps we see in startup device descriptions

Across the technical files that come across Tibor's desk — as an auditor and as a consultant — the same Section 1 failures repeat:

  • An intended purpose written like a marketing tagline. "Helps clinicians make better decisions" is not an intended purpose. It does not name a medical purpose, a target condition, a user group, or an environment. The auditor cannot pin a clinical evaluation to it because there is nothing to pin.
  • A classification rule cited without reasoning. "Class IIa under Rule 11" is an answer. It is not a justification. Annex II expects the reasoning — what software function is performed, what decisions it supports, what the risk level is — not just the verdict.
  • Variants dropped from Section 1 and discovered later in the file. A sales team promises a smaller version, an international configuration, a colour variant, and nobody updates Section 1. The auditor finds the variant in the labelling section or in a test report and asks where it is in the scope. There is no good answer.
  • Materials listed only for the primary component. Patient-contact materials are listed, but indirect-contact materials, internal components, and adhesives are omitted. Annex II asks for materials in key functional elements and in contact with the body. Partial lists are partial compliance.
  • A principles-of-operation section written in marketing language. Sentences that describe what the device does for the customer instead of how it achieves its function. The auditor is reading to understand the mechanism, not the value proposition.
  • Previous generations or similar devices omitted. The manufacturer is silent about the v1 device they placed on the market two years ago, or the competitor product that is visibly similar. Annex II asks for both. Silence is not an acceptable answer.
  • A device description that contradicts the website. The post on common labelling mistakes startups make under MDR covers this in depth. Under Article 2(12), promotional material is part of the intended purpose. A website claim the file does not support is a finding waiting for an auditor to read the site.

None of these are rare. All of them are preventable by treating Section 1 as a tight technical specification that every other section of the file has to remain consistent with.

How to keep Section 1 stable under design changes

A device description that has to be rewritten every design sprint is a device description written too specifically in the wrong places and too loosely in the right ones. The discipline is to separate what is stable from what is volatile.

Stable (belongs in Section 1 narrative): intended purpose, indications, contraindications, patient population, intended use environment, principle of operation, classification rule and its rationale, the variant family definition. These should not change during normal design iteration. If one of them does change, the change is significant enough to warrant a substantive design review and possibly a change notification to the Notified Body.

Volatile (belongs in Section 1 referenced sub-documents): precise dimensions, bill of materials at component level, software build numbers, specific hardware revisions, colour variants within the same family. Reference these from controlled documents under EN ISO 13485:2016+A11:2021 document control, so that when they change, the reference stays valid and only the referenced document moves.

This split — stable narrative, volatile references — is what makes Section 1 survive a product lifecycle. A device description written as one flat prose document contains both stable and volatile content mixed together, so every minor change requires editing the Section 1 narrative, and every edit introduces drift. A device description written with the stable content in prose and the volatile content in linked controlled documents stays clean through dozens of iterations.

One practical tactic: a single controlled document called "device specification" that holds the volatile technical parameters (dimensions, tolerances, component list, firmware version) and is referenced from Section 1 rather than reproduced inside it. The Section 1 narrative points to the specification document at its current version. When the specification changes, the narrative does not.

The Subtract to Ship angle

Section 1 is a section that rewards cutting. The Subtract to Ship framework for MDR applies directly: every sentence in the device description must earn its place by tracing to a specific Annex II Section 1 requirement, to the Article 2(1) medical device definition, to Article 2(12) intended purpose, or to the Annex VIII classification rule. Sentences that do not trace come out.

The result is a device description that is shorter than teams instinctively produce, more precise than teams instinctively write, and more stable than teams instinctively believe possible. Three to six pages of tight Section 1 content, backed by a referenced specification document for the volatile detail, is a common shape for a lean startup device. Fifteen pages of narrative that blends scope, evidence, marketing language, and design history is the shape the file takes when no one has applied the subtraction discipline.

Subtract to Ship is not cutting required content. Annex II Section 1 is specific about what is required, and all of it stays. Subtract to Ship is cutting everything that is not required — and in Section 1, that usually means cutting marketing tone, evidence that belongs elsewhere, and volatile detail that should live in a linked controlled document.

Reality Check — Where do you stand?

  1. Does your current Section 1 contain every element Annex II Section 1 lists — identification, intended purpose, users, patient population, principles of operation, rationale for medical device qualification, classification rule with reasoning, novel features, variants and accessories, key functional elements, materials, technical specifications, previous generations and similar devices? Is any element missing or reduced to a placeholder?
  2. Is your intended purpose written precisely enough that an auditor could read it once and know exactly what condition, user, and environment the clinical evaluation must cover?
  3. Does your classification rule citation include the reasoning that led to it, or only the verdict?
  4. Can you list every variant and accessory that is intended to be covered by this technical file, and does each one appear in Section 1?
  5. Do the claims on your website, pitch deck, and promotional materials match the intended purpose written in Section 1? When did you last check?
  6. Are the volatile parameters (dimensions, BOM, firmware versions) referenced from controlled documents, or buried in the Section 1 narrative where every change forces a rewrite?
  7. If a competent outsider opened Section 1 today, could they answer in under two minutes: what the device is, what it is for, who uses it, how it works, and under which rule it is classified?

Frequently Asked Questions

What is the device description in MDR technical documentation? Under Annex II Section 1 of Regulation (EU) 2017/745, the device description is the opening section of the technical documentation. It identifies the device and its variants, states the intended purpose, describes the intended users and patient populations, explains the principles of operation, lists materials and key functional elements, cites the classification rule under Annex VIII, and references previous and similar generations. It is the scope-setter for the entire file.

Is the device description the same as the intended purpose? No. The device description answers "what is this device?" The intended purpose answers "what is this device for?" Both belong inside Annex II Section 1, but they are distinct sub-components and should be written as clearly separated text. The intended purpose is defined in Article 2(12) of Regulation (EU) 2017/745 and includes everything the manufacturer communicates about the device's use — labels, IFU, promotional materials.

How long should Section 1 of the technical documentation be? There is no prescribed length. For most startup devices, Section 1 runs three to six pages of tight narrative, plus referenced controlled documents for volatile specifications. A Section 1 that runs fifteen pages of prose usually signals that evidence or volatile detail has leaked into it from sections that should hold it.

Do I need to list competitor devices in the device description? Annex II Section 1 requires "a reference to previous generations of the device" placed on the market by the same manufacturer, "as well as a description of similar devices available on the Union or international markets." The level of detail has to be sufficient to understand lineage and context. Silence on similar devices is not acceptable when similar devices clearly exist.

Where does the classification rationale belong — Section 1 or a separate document? The rationale for the risk class and the specific Annex VIII rule applied belongs in Section 1. Some teams keep a longer classification analysis in a separate document and reference it from Section 1; that is acceptable as long as the Section 1 narrative states the rule and the reasoning, and the referenced document adds detail rather than introducing anything new.

What happens if Section 1 contradicts the website? Under Article 2(12) of Regulation (EU) 2017/745, the intended purpose is set by the data supplied by the manufacturer "on the label, in the instructions for use, or in promotional or sales materials or statements." The website is within scope. If the website claims something the technical file does not support, the auditor reads the website as part of the intended purpose and writes the finding accordingly. The fix is to bring the two into alignment before submission, not after.

Sources

  1. Regulation (EU) 2017/745 of the European Parliament and of the Council of 5 April 2017 on medical devices, Article 2(1) (definition of medical device), Article 2(12) (definition of intended purpose), Annex I (General Safety and Performance Requirements — contextual scope for Section 1 content), Annex II Section 1 (device description and specification, including variants and accessories), Annex VIII (classification rules). Official Journal L 117, 5.5.2017.
  2. EN ISO 13485:2016 + A11:2021 — Medical devices — Quality management systems — Requirements for regulatory purposes. Document control requirements that govern how Section 1 references to volatile controlled documents are kept current.

This post is part of the Technical Documentation & Labeling cluster in the Subtract to Ship: MDR blog. Authored by Felix Lenhard and Tibor Zechmeister. Tibor has written and reviewed device descriptions from both sides of the Notified Body table. Section 1 is the section he tells every startup to get right before they write anything else in the file, because every other section inherits its scope from it.