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

The description adds meaningful behavioral context beyond the annotations: it states the tool simulates a browser, returns the main response status, all Access-Control-* headers, the tested origin, and the preflight OPTIONS response. This informs the agent about the tool's output and behavior, complementing the readOnlyHint and destructiveHint annotations.

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 two sentences, front-loaded with the primary purpose, then lists return values and usage guidance. Every sentence adds value with no redundancy or fluff.

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?

With an output schema present and full schema coverage, the description covers purpose, behavior, and typical usage. It's complete for a simple diagnostic tool, though it could optionally mention error handling or network failure behavior for full completeness.

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?

The input schema already provides descriptions for all three parameters (url, method, origin), with 100% coverage. The description doesn't add any additional parameter-specific details, so it meets the baseline but doesn't exceed it.

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 clearly states the tool's function: checking CORS configuration like a browser would. It mentions the resource (URL) and specific action, but doesn't explicitly distinguish itself from the sibling 'cors_test' tool, only from security auditing in general.

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?

The description gives a clear usage context ('Use this for direct CORS debugging') and hints at an exclusion ('not just security auditing'). However, it does not name specific alternative tools, so it lacks explicit when-not-to-use instructions relative to siblings.

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