Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), and the description goes well beyond them: it enumerates the exact validation rules, the failure modes (missing, empty, oversized, non-HTML) and that they return an error, plus the meaning of needsConfirmation and the required user confirmation step via previewUrl.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the validation purpose, then failure behavior, then next steps in a logical order with no filler sentences. It is dense and repeats the return field list that the output schema already declares, which costs a point on strict economy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given a one-parameter read-only validation tool with an output schema present, the description supplies everything an agent needs: purpose, validation contract, error handling, the needsConfirmation workflow, and the two possible follow-up calls. No behavioral gap remains.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the single uploadId parameter is undocumented structurally. The description contextualizes it ('an uploaded design snapshot' and its reuse in propose_usability_test/relaunch_usability_test), which implies it is the upload identifier, but it never states where uploadId comes from or its format.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Verifies an uploaded design snapshot') and immediately narrows scope with the validation criteria (exists, non-empty, self-contained HTML, within size limit). This clearly separates it from siblings upload_design_snapshot and prepare_design_snapshot, which produce artifacts rather than validate them.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly routes the agent after success: propose_usability_test(uploadId) for a new test versus relaunch_usability_test(projectId, uploadId) for an existing project, and gives the recovery path on failure ('re-upload and check again'). It does not explicitly state the ordering relative to upload_design_snapshot/prepare_design_snapshot, so it falls just short of full when/when-not coverage.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.