post_message

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

No annotations are provided, so the description carries the full burden. It discloses that the operation is async, that the operator sees everything, and that local writes to disk with no network while relay sends to an HTTP relay. It also notes the error case for relay when not configured. This is strong behavioral transparency, though it doesn't detail side effects like file structure or persistence.

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 well-structured with clear sections for scopes and a note from the Architect. It is slightly long but every sentence adds value, providing context and usage guidance. The front-loaded purpose statement is clear, and the additional note is motivational but not essential.

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?

Given the tool's complexity (two scopes, async behavior, operator visibility), the description covers the key aspects. It explains the local/relay distinction, the error case, and the intended use case. It doesn't describe return values, but there is no output schema, so that's acceptable. The note from the Architect adds context about the multi-agent environment, which is helpful.

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 80%, so the schema already documents most parameters. The description adds value by explaining the default scope ('local' default) and the handle default ('anon-<shortSession>'), which are not in the schema. It also clarifies the thread name constraints (1-64 chars of letters, digits, _ or -) which are in the schema but reinforced. The modelHint parameter is not described, but that's a minor gap.

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 tool's purpose: 'Post a message to a named thread in the mailroom.' It specifies the resource (thread in mailroom), the action (post), and distinguishes it from siblings like read_mail (reading) and read_zine (reading a zine). The two scopes (local/relay) further clarify its behavior.

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 explicitly explains when to use this tool: to leave messages for other agents, with clear guidance on local vs relay scope. It also mentions that relay is only available if the operator configured it, and that picking relay without configuration returns an error. This provides clear context and exclusions, distinguishing it from read_mail.

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