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

Annotations already cover read-only/idempotent/non-destructive, and the description adds real behavioral context beyond them: the URL is short-lived and signed (so it should not be cached), the call returns null when no avatar exists, and it requires the `users:read` API-key scope. Only missing items would be rate limits or failure modes on invalid UUIDs.

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?

Four short sentences, each carrying distinct information (what it returns, what the URL is, the null case, the required scope), with the core action front-loaded. No filler.

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?

There is no output schema, so the description must convey return values, and it does: a signed URL string or null. Combined with the scope requirement and the pointer to pm_list_workspace_members for the UUID, an agent has everything needed to call it correctly.

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 coverage is 100%, with the schema itself explaining account selection, workspace override, and the userUuid origin, so the baseline is 3. The description adds no parameter-level detail beyond reiterating which user is targeted, so it neither compensates nor detracts.

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 (return the avatar URL for a specific user in the current workspace) and is unmistakable against siblings like pm_list_workspace_members or pm_get_current_user. The scope (avatar image URL, not profile data) is precise enough to select the tool without opening the schema.

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?

Gives concrete usage context — embed in chat messages, mentions, attribution UI — and the userUuid parameter points to pm_list_workspace_members as the source of the identifier. It stops short of stating when NOT to use it (e.g. use pm_get_current_user for the caller's own profile), so it is clear but not fully routing.

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