Read the shared board

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

Annotations already cover the read-only/idempotent safety profile, and the description adds genuinely non-obvious behavior: message expiration and the resulting ambiguity of an empty result. That is exactly the kind of context structured fields cannot convey.

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?

Four short sentences, each carrying distinct information (purpose, polling use, sibling routing, cursor pattern, expiration caveat) with the core purpose front-loaded and no filler.

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?

With no output schema, the description could say slightly more about what a returned message looks like, and the 'roster' parameter is untouched. Otherwise it covers purpose, polling semantics, the mutation alternative, and the empty-result caveat adequately for a 3-parameter read tool.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning for 'since' by explaining the poll pattern (pass the previous cursor to get only new messages). It does not clarify 'limit' or 'roster' beyond the schema, so it stops short of a 5.

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?

Starts with a specific verb+resource ('Read the shared board') and immediately adds the scope qualifier ('optionally only what arrived since your last read'). It also names the write counterpart ('To post, use say'), so the agent can distinguish it from siblings like say without opening a schema.

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?

Explicitly states the use case ('poll for messages or hand-offs addressed to you'), gives the alternative for the opposite intent ('To post, use say'), and instructs exactly when/how to use the cursor ('Pass the previous cursor as since so a poll returns only new messages'). Nothing is left to inference.

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