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

Annotations already cover idempotency and non-destructive/write semantics, but the description adds genuinely new context: it is free, rate-limited, asynchronous, and the first probe runs within minutes. That timing/rate-limit detail is what the agent most needs. Only minor gap is no mention of what a submission returns, though a separate output schema exists.

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?

Tight and front-loaded: cost/limit caveat first, then the action, then when/when-not/after in short clauses. Every sentence carries operational signal with no filler.

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 single-param submission tool with an output schema present, the description fully covers cost, rate limits, selection criteria, exclusions, follow-up, and idempotency. Nothing an agent needs to call it correctly 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?

Single required parameter with 100% schema coverage, so the schema already documents 'url' fully. The description implies the URL must be an x402 endpoint, which aligns with the schema but adds no syntax or format detail beyond it. Baseline 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?

States a specific verb and resource: 'Queue an x402 endpoint URL for indexing.' The x402 qualifier and the 'indexing' action distinguish it cleanly from siblings like settled_check and settled_peek.

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?

Explicit when-to-use ('settled_check or settled_peek reports the URL as unknown or not indexed'), explicit when-not ('URLs already indexed... or non-x402 URLs'), and a follow-up step ('wait a few minutes, then call settled_check'). Nothing is left to inference.

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