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

Annotations already declare readOnlyHint=true and idempotentHint=true, and the description adds meaningful context: it performs a live fetch from a real China egress, reports specific metrics, and frames the result as a measurement rather than a guess. No contradictions with annotations. It does not mention rate limits or failure behavior, but annotations cover safety.

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, front-loaded with the action verb, and every word earns its place. No redundancy or 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?

The tool is simple (1 parameter, output schema provided). The description fully explains the tool's purpose, the measurement approach, and the key limitation of alternatives. Return values are already covered by the output schema, so no further detail is needed.

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 description coverage is 100% with the 'url' parameter described as 'Full URL to test, e.g. https://example.com'. The description restates the URL-fetching concept but doesn't add new parameter-level detail or format constraints beyond the schema. Baseline 3 is appropriate.

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 a specific action ('Fetch a URL from a real mainland-China network egress') and the resource/scope ('URL reachability from China'), with measurable outputs (HTTP status, latency, DNS resolution). This distinguishes it from all sibling tools, which are unrelated to network testing.

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 clarifies when to use the tool: to answer 'is my site/API usable from China?' and explicitly notes that a VPS abroad cannot provide this measurement. While it doesn't name a specific alternative tool, it gives strong contextual guidance and an implicit exclusion.

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