url_status

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

With no annotations, the description carries the behavioral load well: it discloses cost ($0.005 USDC per call), p99 latency (1200ms), and the returned payload. It doesn't state auth requirements or rate limits beyond latency, leaving a small gap, but the cost/latency/return disclosure is genuinely useful context an agent needs before calling.

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?

Front-loaded purpose, then return fields, use cases, params, and cost/latency — every sentence earns its place with zero padding. The em-dash structure keeps it scannable.

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?

For a 2-param tool with no output schema and no annotations, the description is complete: it names the return fields, the cost, and the latency so the agent can make an informed call. Nothing essential for correct invocation is missing.

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 only 50% (only 'url' is described). The description restates params — 'url (required), method (GET default, or HEAD)' — but adds no semantics beyond the schema, such as when HEAD is preferable (cheaper, no body). It compensates partially by enumerating both params, but adds little real meaning.

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+resource ('check whether a URL is reachable') and enumerates exactly what it returns: final status code, redirect chain, response time, content-type, server header, content length. This clearly separates it from siblings like screenshot, web_scrape, and webpage_reader.

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 explicit use cases (link validation, uptime checks, canonical URL resolution) and an alternative-selection rule: run it 'before spending money on a scrape/screenshot.' The agent knows both when to use it and when a costlier sibling is preferable.

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