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

Goes meaningfully beyond the annotations: annotations only declare idempotent/non-destructive/non-readOnly, while the description adds the Bearer writer-token auth requirement, the exact idempotency key tuple, and what is returned. It omits failure modes (what happens on a duplicate or a rejected token), so not a 5.

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 short sentences, all front-loaded and load-bearing: purpose, auth, idempotency key, return. No filler or restatement of the tool name beyond the necessary scope statement.

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?

Auth and idempotency are well covered and annotations carry the safety profile, but there is no output schema and 'Returns the receipt' does not describe the returned shape or key fields. For an 8-parameter mutation with an open-ended subject_type, that leaves a real gap for an agent that needs to chain verify_receipt afterwards.

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 already 100%, so the baseline is 3, but the description adds genuinely new semantics by enumerating which fields compose the idempotency key (writer, subject, subject_type, market, rule_version, cleared_at, answer_hash), which the schema does not state. 'writer' is also mapped to the token implicitly, though caller/caller_key interplay is left 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 and resource — 'Write one v1 receipt for a read a gate has cleared' — which clearly distinguishes a write from the sibling reads/verifications (list_receipts, verify_receipt, get_statement). It does not explicitly name those siblings, and 'v1 receipt' / 'gate' assume domain familiarity, so it stops short of a 5.

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 phrase 'for a read a gate has cleared' implies a precondition for use, and the auth header requirement is stated, but there is no explicit when-to-use guidance, no mention of when not to write a receipt, and no routing versus verify_receipt or list_receipts.

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