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

Annotations already declare readOnlyHint=true, but the description adds substantive context: nothing is written, the call is repeatable safely, listing titles are untrusted citizen text, the return is untrusted citizen-authored data, and CallToolResult _meta carries a server-owned provenance boundary. These are meaningful behavioral disclosures beyond the annotation.

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?

The description is front-loaded with purpose and then kind-specific field mappings; the length is justified by 14 parameters and multiple signing modes. There is some redundancy: 'READ-ONLY' restates readOnlyHint and 'Nothing is written' overlaps with it.

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?

Given high complexity, 14 parameters, 0% schema description coverage, and no output schema, the description covers purpose, per-kind fields, safety, and provenance. But it omits the payout_wallet enum value and does not describe the returned bytes shape, leaving material gaps.

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 0% across 14 parameters, so the description must compensate. It does map field names to the payout, listing, and funder_statement kinds and notes verifier_price_atomic as optional, but it omits payout_wallet and gives no type, unit, or format details, so compensation is only partial.

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 builder for signed payout rail sentences and names three kinds with their field sets. However, the schema enum also includes payout_wallet, which the description never mentions, and it does not explicitly distinguish this tool from sibling payout/signing tools.

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?

Explains for each described kind who signs and when: payee signs payout bytes, funder wallet signs listing proof-of-funds bytes, and paying wallet signs after transfer. It provides no when-to-use-vs-alternatives guidance or exclusions, so usage is implied rather than explicit.

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