update_users_avatar

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

The annotations already establish that this is a non-read-only, non-destructive, idempotent operation, so the description does not need to restate that. It adds the behavioral hint that the body fields must be discovered via a GET or schema endpoint, but it does not disclose authentication requirements, side effects, or response behavior beyond what annotations and the output schema cover.

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?

The description is compact and front-loaded: the purpose appears in the first two words, followed by the HTTP method/path and a single useful parameter note. There is no repetitive or filler content; every sentence earns its place.

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 that the body schema is intentionally open (additionalProperties: true, openWorldHint: true) and an output schema exists, the description adequately points the agent to the correct discovery mechanism before calling. The main shortfall is the vague 'matching GET' reference, which relies on the agent inferring the correct GET endpoint from the URL path.

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?

The input schema provides no property details for the body beyond additionalProperties: true, so the description must compensate. The line 'Request payload. Read the matching GET or the /schema endpoint first to see the fields this resource expects' gives the body real meaning: it is the resource representation whose fields are defined externally. It could be stronger by naming the exact matching GET endpoint, but it provides actionable guidance.

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 states a clear verb and resource ('Update avatar') and cites the HTTP endpoint (PUT /users/avatar), so an agent knows what action is being performed. It does not explicitly differentiate from similar-looking sibling tools such as update_users_set_cover, but 'avatar' is a distinct enough resource to avoid major ambiguity.

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?

The description gives practical usage context: read the matching GET or /schema endpoint first to learn the expected fields. However, it does not say when to prefer this tool over alternatives or describe exclusions, leaving some inference required.

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