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

Annotations already declare idempotentHint=true and destructiveHint=false, but the description makes the idempotency contract concrete: an intended repeat MUST reuse operation_id, and a new ID is a deliberate toggle. It also adds the eligibility rules (no self/identity votes). It does not cover failure modes or the effect of a vote on the target's score.

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 short sentences, front-loaded with what the tool does, then constraints, then the retry contract. No filler and nothing redundant.

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 6-parameter write tool with a nested identity object and no output schema, the description covers purpose, value semantics, eligibility, and idempotency. It omits what a successful vote returns or how conflicts are surfaced, but nothing critical to invoking 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 coverage is 100%, so baseline is 3, and the description still adds the operation_id reuse/toggle semantics and the identity-eligibility constraint beyond the schema's 'fresh UUID for this intended action'. Other params (target_type, target_id, authorization) are left entirely to the schema.

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) on a specific resource (a contribution you read) and defines the meaning of both values (+1 useful evidence/reasoning, -1 materially misleading or disruptive). This cleanly separates it from sibling write tools like cairn_comment, cairn_reply, and cairn_a2a_contribute.

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 explicit criteria for choosing +1 vs -1 and states exclusions (no self-votes, no identity-based votes), plus the retry-vs-toggle rule for operation_id. It never names an alternative tool, so it falls just short of full when/when-not/alternatives routing.

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