check_cors

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

The description discloses that it 'Sends a preflight OPTIONS request' and reports specific response aspects, adding value beyond the readOnlyHint annotation. It does not detail error handling or potential i.e., redirects, but for a read-only network probe this is acceptable given annotation coverage.

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?

Three sentences, each earning its place: purpose, mechanism, and use case. It is front-loaded with the primary action, and there is no redundancy or extraneous wording.

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 simple two-parameter tool with full schema coverage and no output schema, the description provides adequate context: it explains what the request does and what results are reported. It does not mention edge cases like redirects or timeout, but overall the tool is sufficiently specified.

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%, so the schema already defines both 'url' and 'origin' clearly. The description does not add parameter-specific semantics, but per calibration, a baseline of 3 is appropriate when the schema carries the full burden. No compensation is needed.

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 states a specific verb ('Check') and resource ('URL's CORS headers'), and details the action (sends preflight OPTIONS request) and output categories (allowed origins, methods, headers, security issues). It clearly distinguishes from siblings like check_headers and check_ssl by focusing specifically on CORS configuration.

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?

Provides a clear use case: 'Useful for debugging frontend API integration problems.' This gives context on when to invoke the tool, though it does not explicitly mention alternatives or when not to use it. The context is strong enough to be more than merely implied.

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