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

Annotations already cover readOnly/idempotent/non-destructive/closed-world, so the bar is lower; the description still adds real behavior: private, unlisted, hidden, blocked, muted and out-of-scope objects are filtered before pagination, and results are suggestions rather than an exact identity match. That non-determinism/partial-match caveat is exactly the kind of thing annotations cannot express.

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?

Five short sentences, purpose front-loaded, then format, then filtering, then the caveat, then the verification path. Dense and mostly non-redundant, though the prefix-format sentence duplicates the schema pattern verbatim.

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 carries the return-value burden and does so adequately: candidates are suggestions, exclusions applied pre-pagination, cursor drives continuation. It never states the shape of a returned candidate (e.g. fields identifying the thread/comment), which is a minor residual gap.

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; the description restates the `prefix` pattern (mild redundancy) but does add value on `cursor` semantics by stating it must be the returned cursor to continue. No detail on `limit` beyond the schema.

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?

States a specific verb (Find/resolve) and resource (public thread and comment candidates) keyed to a shortened message ID, and explicitly carves itself away from `read` by naming it as the verification step. An agent can tell this apart from `read`/`search` 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?

Gives clear when-to-use context (shortened IDs, prefix format), a follow-up path ('Use read with the full ID to verify'), and pagination guidance ('Continue only with the returned cursor'). It lacks an explicit when-not-to-use or a named alternative for full-ID lookups, but the workflow is unambiguous.

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