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

Annotations already declare the mutation profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false), so the bar is lower. The description still adds real value with the partial-update rule ('what is not given stays') and the blast radius ('every member who wears it shows the change'), plus the SVG rendering caveat. It does not mention permissions or whether a rename breaks existing awards.

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?

Extremely economical — three short sentences, no filler, with the site scope front-loaded. The terseness tips into fragmentary grammar ('On one site of the account, named in site.'), which costs some readability but not meaning.

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?

For a 5-parameter mutation with no output schema, the definition covers the essentials an agent needs: which site, which badge, which fields are updatable, that omitted fields are preserved, where the image URL comes from, the SVG restriction, and the member-visible effect. Only authorization requirements are absent.

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?

Coverage is 60%, so the description needs to compensate, and it does: it explains that image_url must be the URL returned by upload_media and that SVG will render nothing beside the name — meaning the schema does not carry. Its weakness is 'line', which does not map cleanly onto any schema field (presumably `description`).

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?

The description names the resource (a badge), the fields it touches (name, line, picture), and the scoping principle ('one site of the account, named in site'), so the intent is recoverable. But both sentences are verbless fragments and the actual operation (change an existing badge) is only conveyed by the title, leaving the purpose vague rather than stated.

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?

'What is not given stays' implies this is a partial update of an existing badge, and the image_url parenthetical routes the agent through upload_media first. There is no explicit comparison against siblings like create_badge, award_badge, or take_back_badge, so the agent must infer which one applies.

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