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

Annotations already disclose that this is a non-idempotent, destructive write operation. The description adds useful context about the permission effect (agent can see and reply to conversations), but does not explain failure modes (e.g., duplicate membership) or permission requirements.

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?

A single, well-structured sentence that front-loads the action and includes only relevant consequence. No wasted words or redundancy.

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 simple two-parameter write tool with rich annotations and no output schema, the description covers purpose and effect but leaves a gap by not mapping the parameters (especially user_id as agent ID) despite zero schema descriptions. An agent can infer the mapping but may hesitate on the user_id parameter's meaning.

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 description must compensate but does not. It mentions 'agent' and 'inbox' which loosely map to the user_id and inbox_id parameters, but does not clarify that user_id is the agent's ID, nor does it explain the integer format or constraints.

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 clear verb (add) and resource (inbox member) and adds the effect: the agent can see and reply to conversations. It is specific enough to distinguish from most siblings, though it does not explicitly differentiate from closely related tools like remove_inbox_member or update_agents_in_inbox.

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 no guidance on when to use this tool versus alternatives such as update_agents_in_inbox (bulk updates) or remove_inbox_member. It only implies usage from the verb, with no exclusions or prerequisites stated.

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