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

Annotations already establish readOnly/idempotent/non-destructive, but the description adds substantive behavior beyond them: private, unlisted, hidden, blocked, muted, and out-of-scope objects are excluded before pagination, and results are non-authoritative suggestions. It does not mention rate limits or return shape, keeping it out of the top band.

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 tight sentences, front-loaded with purpose, then input format, filtering behavior, the suggestion caveat, and verification/pagination guidance. 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 still conveys that results are candidate suggestions and that a cursor is returned for continuation, which is enough to call it correctly. It reasonably omits nothing critical, though it could say more about the candidate result shape.

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 all three parameters are already documented; the description's restatement of the msg_ pattern duplicates the schema. It adds only a marginal operational note for the cursor ('continue only with the returned cursor'), so the baseline 3 applies.

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 names a specific verb (Find) and resource (public thread and comment candidates) scoped to a shortened message ID. It also implicitly distinguishes itself from the sibling `read`, which is reserved for verification with the full ID.

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?

It gives clear operational guidance: pass a msg_-prefixed ID, treat results as suggestions rather than exact matches, verify with `read` using the full ID, and continue only with the returned cursor. What's missing is explicit routing versus siblings like `search` or `run_search`, so the when-not-to-use case is inferred.

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