send_inbox_message

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

With no annotations, the description carries the full burden, but it only states the routing modes and does not disclose side effects, parameter precedence, or behavior when both routing params are provided. The existing_thread_only flag is also not explained, so the agent has limited understanding of what happens at runtime.

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 a single sentence with no filler, front-loading the main action and routing options. Every word adds value and it is efficiently written.

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?

The tool has 5 parameters, no output schema, and no annotations, yet the description only mentions two routing modes. It does not explain required vs optional params, what happens if both conversation_id and participant_profile_url are provided, or what the response looks like. The description is inadequate for an agent to use this tool confidently.

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 already provides detailed descriptions for each parameter (e.g., 'routes directly to thread', 'routes via profile compose flow'), and the description merely summarizes these. Since schema coverage is 100%, the description adds no additional semantic meaning beyond what is already structured, so the baseline 3 applies.

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 clearly states a specific action ('Send a message') and specifies two distinct routing mechanisms ('conversation-id thread routing' or 'profile-url compose routing'), which differentiates it from the generic sibling send_message. It is concise and unambiguous about what the tool does.

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 implies usage based on the two routing modes (conversation_id vs participant_profile_url), but does not explicitly say when to prefer this tool over the sibling send_message. It lacks exclusions or alternative guidance, leaving it up to the agent to infer.

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