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

Beyond the readOnly/idempotent annotations, the description discloses that it does not execute or approve payment, never treats missing evidence as safe, may return stale evidence, and explicitly lists UNKNOWN fields. It also notes that third-party probe observations are not independently verified settlements. No annotation contradiction.

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 dense but every clause carries critical caveats: read-only nature, UNKNOWN fields, staleness, pilot scope, and non-execution. It front-loads usage context before caveats. Slightly long, but each sentence earns its place.

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?

The description covers when to use it, return contents, explicit unknowns, data freshness, limitations, and a full invocation example. With a rich output schema already provided, nothing needed for correct invocation 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% with detailed per-parameter constraints (e.g., USDC-only, CAIP network, exact URL matching). The description's invocation example duplicates the schema example and adds no new parameter semantics, so the baseline of 3 applies.

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 uses a specific verb ('preflight'/'compare') against a clear resource (a proposed machine payment and MEO's dated economic history) and states what it returns. It also explicitly negates execution/approval, leaving no ambiguity that this is a read-only assessment tool.

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?

‘Before paying an unfamiliar machine service’ gives a concrete invocation context, and the pilot-scope note further narrows applicability. There are no sibling tools, so alternative routing is unnecessary; a when-not-to-use exclusion is not explicitly stated, but the context is clear.

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