Probe an HTTP(S) URL

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

Adds real information beyond the annotations: the response body is not returned, redirect hops are re-validated, and probed-site content (titles, headers, DNS records, file contents) is untrusted data rather than instructions. That prompt-injection caveat is a substantive disclosure no annotation conveys. 'Read-only' merely echoes readOnlyHint but is harmless.

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 tight sentences, front-loaded with the core behavior, followed by the usage framing and the safety caveat in the position an agent will actually read. Nothing is padded; the only near-redundancy is the two-word 'Read-only'.

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 no output schema, the description compensates by enumerating the returned fields, and it flags the body-not-returned limitation so an agent does not expect page content. For a four-parameter read tool this is complete.

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 75%; url, follow_redirects and allow_invalid_cert already carry descriptions. The description supplies meaning for the one undocumented parameter, 'method', by stating the request is GET or HEAD, and clarifies that redirect-chain reporting pairs with follow_redirects. It adds modest but genuine value over the schema.

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 ('makes one GET or HEAD request') and enumerates exactly what is reported (status, redirect chain, timings, headers, size, page title, robots meta). The explicit 'response body is NOT returned' line and the tls_inspect pointer let an agent separate this from tls_inspect, redirect_chain, and security_headers without opening a schema.

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 concrete trigger questions ('is this URL up, where does it redirect, how fast is it?') and cross-references tls_inspect for certificate diagnosis. It stops short of naming exclusions against other siblings — notably redirect_chain and security_headers, whose scope overlaps with what this tool reports.

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