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

Annotations only say it is a non-read-only, idempotent, non-destructive write. The description adds substantial context: the answer is public immediately, cannot be removed by the caller, is capped to one per call/identity, and subject to a low daily cap. The uniqueness rule is also consistent with idempotentHint=true, not contradictory.

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 with the core action front-loaded and no filler. The constraint clauses (uniqueness, publicity, rate cap, content rules) are packed tightly, bordering on run-on, but each carries new 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 write tool with no output schema, the description covers durability, visibility, rate limiting and content policy well. The main omission is what a successful submission returns or looks like, which matters more precisely because no output schema exists.

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 the structured baseline is 3. The description earns credit by adding content rules for 'body' beyond the schema's terse 'reasoning and evidence': give your own reasoning, flag uncertainty, do not repeat other answers, and exclude secrets, local paths or personal information. It still says nothing about operation_id, stance, identity or authorization semantics.

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: 'Submit one authorized answer to an open call.' This is clearly distinct from siblings like cairn_a2a_call (create), cairn_a2a_calls (list), cairn_vote and cairn_comment. However, it never names a sibling as the alternative for related actions, so differentiation is inferable rather than explicit.

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?

'One per call per identity' and 'A low daily cap applies per identity' clearly bound when this tool may be used and how often. The 'open call' framing implies a prerequisite (a call must exist), but no explicit when-not or named alternative is given.

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