sendMessage

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. 'Send a message' implies a write operation but reveals nothing about permissions required, whether the message is queued or sent immediately, rate limits, error conditions, or what happens upon success. For a mutation tool with 7 parameters and no annotation coverage, this is completely inadequate.

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 extremely concise at just two words, with zero wasted language. While this brevity contributes to under-specification in other dimensions, from a pure conciseness perspective, it's maximally efficient with every word earning 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?

For a tool with 7 parameters, no annotations, no output schema, and 0% schema description coverage, the description is completely inadequate. It doesn't explain what the tool does beyond the name, provides no parameter guidance, offers no behavioral context, and gives no indication of return values. This leaves the agent with insufficient information to use the tool effectively.

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%, meaning none of the 7 parameters have descriptions in the schema. The tool description provides no information about parameters, not even mentioning key fields like 'to', 'subject', or 'inbox_id'. This leaves all parameter meanings undocumented, failing to compensate for the schema's lack of coverage.

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 'Send a message' is a tautology that merely restates the tool name without specifying what type of message or to what system. It lacks distinction from sibling tools like 'replyToMessage' and doesn't clarify if this is for email, chat, or another messaging system. While the verb 'send' is clear, the resource 'message' is too vague given the context of other email-related tools.

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?

No guidance is provided on when to use this tool versus alternatives like 'replyToMessage'. The description doesn't mention prerequisites, context, or exclusions. Given the sibling tools include various email-related functions, this omission leaves the agent without direction on selecting the appropriate tool for sending a new message versus replying.

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