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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The phrase 'One check per link' hints that each URL consumes an individual check against a quota, but the daily limit (mentioned only in the api_key parameter) and any failure behavior are not surfaced in the description.

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 short sentences, front-loaded with the batch limit and the identifying use case. 'One check per link' is terse and slightly cryptic but does carry quota-relevant information, so it earns its place.

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 should explain what a 'check' yields (status code, safety verdict, per-link results). It leaves the return shape entirely unspecified, though the core invocation semantics are clear enough.

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 50%: api_key is fully documented in the schema, while urls has no schema description. The description partially compensates by saying these are links and that up to 50 are allowed, which matches maxItems=50, but adds nothing about malformed URLs or duplicate handling.

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 with scope: check up to 50 links in one call. The batch scope implicitly contrasts with the singular check_url sibling, but does not name it explicitly.

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?

Provides a concrete use case (a page of search results), which implicitly tells the agent to use this for batches rather than single URLs. However, it never states when not to use it or names an alternative such as check_url for a single link.

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