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

With no annotations, the description carries the full burden of behavioral disclosure. It does this well: follow redirects (max 4), block private/internal addresses, report specific fields, and operate anonymously. This reveals key runtime behavior and restrictions. A minor gap is the lack of timeout or error-handling detail, but for a simple liveness probe this is solid.

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 concise sentences, approximately 25 words. The core purpose is front-loaded, followed by behavior details, then restrictions and cost. Every sentence adds value, with no filler or repetition.

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?

The description covers the tool's purpose, behavior, restrictions, and the exact output attributes, which is notable given there is no output schema. It is complete enough for an agent to correctly invoke the tool and interpret results. The only missing context is timeout behavior and possible error responses, but for a 1-parameter, read-only probe this is a minor omission.

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%, so the baseline is 3. The description adds meaningful semantics beyond the schema by specifying that the URL must be public, redirects are followed up to 4 hops, and private/internal addresses are blocked. This informs parameter constraints that the schema does not fully express.

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 opens with 'Liveness probe for a public URL', a specific verb+resource pairing that immediately conveys what the tool does. It further enumerates the exact outputs (final URL, status, latency, content type), making it easy to distinguish from the unrelated sibling tools. No ambiguity remains.

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?

Usage context is implied: this is a liveness probe for public URLs, and the 'Free, anonymous' note hints at when it might be appropriate. However, it does not explicitly state when to prefer this tool over alternatives or name any exclusions beyond the address block. Guidance is present but not fully explicit.

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