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

Beyond the annotations (readOnlyHint, openWorldHint, etc.), the description adds meaningful behavioral context: it invokes a 'safe fetch transport', states it does not execute JavaScript or bypass access controls, and clarifies caching behavior via the 'fresh' parameter. This adds valuable operational nuance.

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 two sentences, front-loaded with the core purpose and followed by necessary usage constraints. Every sentence earns its place with 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?

Given the simple tool (2 params, output schema exists), the description covers purpose, usage constraints, and operational behavior. It is sufficiently complete for an agent to select and invoke the tool correctly.

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%, so the description doesn't need to explain parameters. The description reiterates 'absolute public HTTP(S) URL' and 'fresh' semantics, but these are already present in the schema. No new parameter insights are added.

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: 'Report HTTPS certificate validation performed by the safe fetch transport.' This identifies the verb (report) and resource (HTTPS certificate validation), distinguishing it from siblings like web.url.headers or web.url.status.

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?

It provides explicit usage constraints: 'Use only for public HTTP(S) resources' and explains what it doesn't do ('does not execute JavaScript or bypass access controls'). It also advises on the 'fresh' parameter. However, it doesn't explicitly name alternative tools, though the constraints help an agent decide when to use this tool.

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