send_message

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

With no annotations provided, the description carries full burden for behavioral disclosure. While it mentions the API key requirement (useful context), it doesn't describe what happens when a message is sent - whether it's visible immediately, triggers notifications, has rate limits, or requires specific permissions beyond the API key. For a mutation tool with zero annotation coverage, this is insufficient.

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 sentences, with the core purpose stated first and the key requirement following. There's no wasted language, though it could potentially benefit from slightly more context given the mutation nature of the operation.

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 mutation tool ('send' implies creation/writing) with no annotations and no output schema, the description is incomplete. It doesn't explain what the tool returns, what side effects occur, or provide sufficient behavioral context. The API key mention helps but doesn't compensate for the significant gaps in understanding this tool's full behavior.

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 100%, so the schema already documents all three parameters thoroughly. The description adds no additional parameter information beyond what's in the schema. According to scoring rules, when schema coverage is high (>80%), the baseline is 3 even with no param info in the description.

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 the action ('Send a message') and target ('to a listing'), making the purpose immediately understandable. However, it doesn't differentiate this tool from sibling messaging tools (none exist in the provided list), so it doesn't fully distinguish itself from potential alternatives.

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 mentions 'Requires API key' which provides some context about prerequisites, but offers no guidance on when to use this tool versus alternatives like 'get_messages' or 'submit_offer'. There's no indication of appropriate scenarios or exclusions for this messaging function.

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