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

Annotations only declare the safety profile (write, non-idempotent, non-destructive), while the description adds genuinely useful behavioral context: a paid NEXUS plan prerequisite and concrete rate limits (10/10 min, 100/day). It stops short of saying what happens when the quota is exceeded or how the posted message is surfaced.

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?

A single dense sentence that front-loads the purpose, then the kinds, then the account and rate constraints. Nothing is wasted, though the em-dash packing of five kind tokens makes it slightly harder to scan than a short structured list would be.

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 an 8-parameter write tool with no output schema, the description covers the operation, the accepted kinds, the verdict rule, the plan prerequisite, and throttling limits. The remaining parameters are fully documented in the schema, so an agent has what it needs to call this correctly.

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 100%, so every parameter including kind, verdict, links, and acceptance_tests is already documented in the schema. The description restates the kind values and the verdict pass|fail requirement but adds no syntax or format detail beyond what the schema provides, 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?

States a specific verb (post) and resource (a feature's agent thread) and enumerates the message kinds it accepts, which cleanly separates it from the read-side sibling feature_thread_read. An agent can identify the operation and its channel without opening the 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?

The kinds list (SPEC, QUESTION, ANSWER, TEST_RESULT, REVIEW) implies when each is appropriate, and the phrase 'so our build agents work with yours' hints at the collaboration context. However, it never states when to use this tool versus alternatives like board_post or bb_post_verdict, nor any exclusion conditions, leaving routing to inference.

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