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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so safety is mostly covered; the description still contributes the cost profile ("free") and the page-size ceiling, which annotations do not express. It stops short of describing ordering guarantees across pages or staleness of the uptime window, keeping it below 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?

Front-loaded with the payload description, then usage, then the alternative, then the constraint — a sensible order with no filler sentences. The opening sentence is long and list-heavy, which costs some readability but every clause carries information.

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?

Return values need not be explained because an output schema exists, and annotations carry the safety profile; the description fills the remaining gaps — when to call it, what it is not (check_endpoint), cost, and pagination ceiling. Nothing an agent needs to invoke this 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?

Schema description coverage is 100% — host, sort, limit, query, offset, and verdict are all documented with enums and bounds in the schema. The description adds only the 50-per-page cap, which duplicates the schema's limit maximum, 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?

States a specific verb and resource ("List one seller's monitored x402 endpoints") and enumerates exactly what each row carries: grade, score, verdict, 7-day uptime, median response time, real-test-payment status, and check count. It is clearly separable from the siblings: list_sellers spans all sellers, check_endpoint drills into one endpoint's rationale.

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?

Gives explicit sequencing ("Use it after list_sellers") plus two concrete decision scenarios — choosing the best endpoint from a provider and identifying endpoints to avoid. It also names the alternative for a different need (check_endpoint for full reasons), so the routing decision is fully specified.

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