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

Annotations already declare readOnlyHint=true and openWorldHint=true, and the description adds real value beyond them: nothing is copied, the fetch happens at publish time, and the URL must be public https. It does not describe error behavior for unreachable URLs or any rate limits.

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 short sentences, front-loaded with the core action, then the deferred-fetch caveat, then the alternative routing. No filler.

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?

Covers the mutation-free semantics and the alternate path well, but with no output schema the phrase 'reports what it is' leaves the return value under-specified. Otherwise adequate for a single-parameter tool.

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?

Only one parameter and schema coverage is 100%, so the baseline is 3. The description reinforces the 'public https URL' constraint from the schema but adds no format, size, or content-type guidance beyond 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?

States a specific action on a specific resource ('Checks that a public https URL can be fetched') and names the sibling it complements, request_upload_url. Slight ambiguity remains around what 'register' means as a side effect, though 'the network fetches the URL when it publishes' partly resolves it.

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 an explicit when-not condition and the alternative to use instead: 'If you hold bytes rather than a URL, call request_upload_url instead.' That is exactly the routing decision an agent needs.

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