send_message

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

No annotations are present, so the description carries the burden. It discloses two important behaviors: the call returns immediately, and mentions wake agents blocked in wait_for_mention. However, it does not mention return value, failure behavior, or whether any authorization or preconditions apply, leaving gaps for a mutation tool.

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 two short sentences with no filler. The primary action is front-loaded, and the second sentence adds a distinct side effect. Every word earns 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 simple tool with no output schema and no annotations, the description is close but incomplete. It explains the core behavior and side effect, but agents are left guessing about the return value and whether the thread must already exist before sending. The sibling context helps, but the description could be more self-sufficient.

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. It adds meaningful semantics for the 'mentions' parameter by linking it to wait_for_mention, but it does not clarify the exact role of thread_id or content beyond what their names imply. This is partial compensation, not full.

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 states a specific action ('Append a message') and a key behavioral trait ('return immediately'), making the core purpose clear. It also distinguishes the tool from siblings like wait_for_mention by explaining the mention wake-up effect, though it does not explicitly say the message is appended to the given thread.

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?

Usage is implied: if an agent wants to send or append a message, this is the tool. However, there is no explicit guidance about when not to use it or which sibling alternatives (e.g., create_thread vs send_message) apply in different situations.

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