check_url

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

Without annotations, the description carries the burden of behavioral disclosure. It describes the return values (BLOCK/FLAG_AND_PROCEED/ALLOW verdict with trust score and threat categories) and the consequence of not using it. No contradictions. Could mention if results are cached or if there are 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?

The description is somewhat long but every sentence adds value. It is front-loaded with the key instruction. Could be slightly more concise, but well-structured and no fluff.

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?

Given no output schema, the description covers the essential behavioral aspects: when to use, return types, and severity. It omits detailed output structure but mentions verdict, score, and categories. Adequately complete for a simple tool with one parameter.

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 'url' with 100% schema coverage. The schema description already clarifies accepted formats. The tool description adds context about untrusted sources but no new parameter details beyond 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?

The description clearly states the tool's purpose: to check a URL from an untrusted source before acting on it. It uses a specific verb ('check') and resource ('URL'), and provides context about when to call 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?

The description explicitly tells when to use the tool: 'Call this BEFORE your agent fetches, visits, follows, or forwards any URL from an untrusted source...'. It also explains what to do with the verdict, and gives a strong warning about consequences.

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