browser_fetch

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

With no annotations provided, the description carries the full disclosure burden. It usefully discloses that the request runs from the extension background and is exempt from CORS/CSP restrictions. However, it does not mention response format, error behavior, authentication needs, or potential side effects of methods like POST/PUT, which would add meaningful behavioral context.

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?

Three sentences with no filler. The first sentence states the core behavior and the CORS exemption, the second gives the usage condition, and the third provides practical examples. Every sentence 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?

The schema fully documents the four parameters, and the description supplies the essential selection context. The main gap is the lack of return-value or error-handling details, especially since there is no output schema, but for a straightforward HTTP fetch tool the expected response is largely implied.

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 structured schema already documents url, body, method, and headers. The description adds no additional parameter-level meaning, but the fields are self-explanatory and the baseline of 3 applies because the schema handles parameter documentation.

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 states a specific verb and resource: 'Make an HTTP request from the extension background'. It also highlights the key differentiator, 'NOT subject to CORS', which distinguishes it from page-context fetch and other browser tools. It does not explicitly name a sibling alternative, but the purpose is clear and actionable.

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 gives explicit usage guidance: use this when page-context fetch would be blocked by CORS or CSP, and provides concrete examples like Google, Stripe, and Slack APIs. It clearly identifies the condition that selects this tool, even though it does not list alternative tools or exclusion cases explicitly.

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