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

Annotations only declare the non-destructive write profile; the description adds substantial context beyond them: metered billing (monthly AI-draft allowance, then 1 credit per draft), the fact that it never posts, and the auth/plan prerequisites (Indie plan, authorized account or write-scope API key). This is exactly the extra behavior an agent needs.

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?

Opens with a 'WRITE tool' marker, then purpose, then billing, then the routing tip — every sentence carries distinct, load-bearing information with no filler. Dense but appropriately sized.

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 two-parameter mutation tool with no output schema, the description covers purpose, cost, side effects (never posts), prerequisites, and alternatives. Nothing an agent needs to invoke it correctly is missing.

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% and both parameters are documented in the schema, so baseline is 3. The description references the optional hint as 'direction for this draft' but adds no syntax or format detail beyond what the schema already states.

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 and resource ('write a fresh AI reply draft for a review') and immediately clarifies the mechanism (app instructions + optional hint) and translation behavior. It is clearly distinguishable from the write-sibling sonar_update_review_reply, which it names.

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 routes the agent: 'agents can skip this and write the reply themselves with sonar_update_review_reply (not metered)' gives both the alternative and the reason to prefer it. Combined with 'Never posts', the when-to-use/when-not decision is fully specified.

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