check_fbc_url

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

With no annotations, the description carries the full burden and does so thoroughly: 30 s timeout, 20-script cap, 2 MB per file, mobile Safari UA, SSRF guard behavior including redirect hops, and the FBC_GUARD_ALLOW_PRIVATE override. It also explains the meaning of every possible status value, including the subtle distinction that 'unknown' and 'not_applicable' are not passes.

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 purpose is front-loaded in the first sentence, followed by fetch limits, security behavior, and return structure in a logical order. Every sentence carries information an agent needs given the lack of annotations and output schema, and nothing is redundant.

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?

There is no output schema or annotations, so the description must explain behavior and returns itself, which it does in detail. It covers fetch scope, limits, security refusals, status semantics, and the full shape of the JSON response, leaving no material gap for correct invocation or interpretation.

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?

There is only one parameter, and the schema already documents it at 100% coverage as an http or https URL of the landing page. The description adds no format or validation detail beyond the schema, 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?

It names a specific verb (fetch a landing page) and a specific action (run the same checks as check_fbc_code) on HTML plus same-origin <script src> files. It also clearly distinguishes itself from the sibling tool by explaining that external tracking files are included, which the code snippet check cannot do.

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?

It gives a clear positive condition for use: checking a live landing page where tracking code may live in an external file. It also states exactly what is never fetched (cross-origin scripts) and where those appear in the result. It does not explicitly say when to prefer check_fbc_code instead, so a 4 rather than a 5.

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