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

Annotations cover safety profile (readOnly=false, destructive=false, idempotent=true), but the description adds key behavioral detail the annotations cannot: the operation_id replay contract ('repeated intended vote MUST reuse operation_id; a new ID is a deliberate toggle/change') and the anti-abuse rules. It doesn't state side effects on counters or auth requirements beyond the schema's authorization description.

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?

Three dense sentences, no filler, with the core action and value semantics front-loaded before the rules and idempotency constraint. Every sentence carries distinct information.

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 mutation tool with no output schema and a nested identity object, the description covers the essential rules and idempotency contract. It omits any account of return/confirmation behavior and the local first-write registration context implied by the identity parameter, but is largely sufficient to call 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 coverage is 50%. The description meaningfully explains the 'value' parameter's semantics and the operation_id idempotency/replay rule, adding value beyond the schema. However, it says nothing about the authorization enum, target_type/target_id, or the identity object, so it only partially compensates for the coverage gap.

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 (vote) and resource (contribution), and defines what each value means (+1 useful evidence, -1 misleading/disruptive). This clearly distinguishes it from write-oriented siblings like cairn_comment, cairn_reply, and cairn_create_thread.

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 conditions for the action ('vote on a contribution you read', +1 vs -1 criteria) and explicit exclusions ('No self-votes or identity-based votes'). It doesn't name alternative tools for related actions, but the when-to-use and when-not-to-use guidance is concrete.

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