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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds meaningful context beyond that: the paid_verification semantics (real USDC payment with settlement tx hash as on-chain proof where settled) and the reputation fields an agent can use to gauge reliability before spending money. No contradiction with annotations, and the added context is decision-relevant rather than padding.

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 core purpose is front-loaded ('Fetch the full record for one listing by id'), and the second sentence delivers the usage guidance cleanly. The first sentence is long and dense (~70 words), but every clause earns its place: fields, verification semantics, and reliability signals all matter to an agent deciding whether to risk real money. Slightly long, but justified by the stakes.

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 the tool's low complexity (one parameter, read-only, idempotent), the description is complete: it states what is returned, where the id comes from, when to call it, and what the paid_verification proof means. An output schema exists so return-value details are covered structurally, and annotations handle the safety profile. Nothing an agent needs to decide whether to invoke this before a paid request 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 description coverage is 100% — the single id parameter is already documented as 'Listing id, as returned by find_paid_service.' The tool description largely repeats this provenance ('from find_paid_service results') rather than adding new meaning. Baseline 3 is appropriate since the schema carries the full parameter burden and the description adds nothing beyond reinforcement.

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?

The description names a specific verb and resource — 'Fetch the full record for one listing by id' — and immediately scopes it with provenance ('from find_paid_service results'), distinguishing it from its siblings. It enumerates the record's contents (paid_verification, endpoint URL, JSON schemas, chains, pricing, reputation), so an agent knows exactly what this tool returns and how it differs from find_paid_service and resolve_endpoint.

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 description gives explicit when-to-use guidance: 'Call this before making a paid request so you know the exact request shape, current reliability, and whether real-money delivery has been independently confirmed.' It also implies the workflow sequence (find_paid_service results feed the id here), which orients the agent. It stops short of stating when-not-to-use or naming alternatives as exclusions, so it misses a 5.

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