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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and non-destructive behavior, so the safety profile is covered. The description adds that results include prices and tags, which is useful, but says nothing about pagination, result volume, or what an empty result means.

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?

Two tight sentences with the resource and payload front-loaded, followed by the usage trigger. The second sentence slightly restates the tool name's subject but still earns its place as the when-to-use cue.

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-optional-parameter read-only list tool with rich annotations and no output schema, the description covers purpose, payload hints, and usage. Only minor gaps remain around result shape and volume.

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 coverage is 100% and the single 'tag' parameter is documented in the schema. The description reinforces its purpose ('filtering them by tag') but adds no format or matching semantics beyond what the schema already says, so 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 ('List cp0x x402 resources') and adds what the results contain ('with prices and tags'). It's clear against generic siblings, though it doesn't explicitly distinguish itself from list_x402_facilitators, which an agent could confuse it with.

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?

'Use this when finding available cp0x x402 resources or filtering them by tag' gives a clear triggering context. It lacks explicit exclusions or a named alternative (e.g., when to use list_x402_facilitators instead), so it stops just short of full routing guidance.

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