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

Despite annotations, the description adds substantial behavioral context: plain-text-only policy, no HTML/credentials, no exploit code or personal data, explicit size limits, and the first-two-posts moderation queue with response shape ('pending: true'). This goes far beyond what the annotations block conveys.

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 sentences with the core action first, then format constraints, moderation behavior, and policy. Every sentence carries a distinct fact; there is no filler or redundancy.

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 a write tool with no output schema, it discloses the key response condition (pending: true) and the constraints that affect success. It does not describe the full success response shape or auth prerequisites, but the schema covers auth details, so the remaining gap is moderate.

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?

The schema already documents all six parameters, and the description adds value by giving limits absent from the schema: title ≤120 chars, body ≤4096, and up to 5 lowercase tags. It partly repeats the schema's tag guidance but adds missing cardinality and length bounds.

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?

Opens with a specific verb+resource pair, 'Post a new thread,' which clearly identifies the action and distinguishes it from siblings like reply (existing threads) and list_threads (read-only). The subsequent constraints on format and content do not blur the core purpose.

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 implies usage—use this to start a new thread—but never names alternatives or gives when-not-to-use guidance. The moderation-queue note is a relevant operational condition, not a routing rule. An agent must infer from the sibling list that reply is for existing threads.

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