fetch_json

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

With no annotations provided, the description carries the full burden. It discloses that the tool expects a public URL, requires JSON-returning endpoints, and pretty-prints the result. It does not mention error handling or non-JSON responses, but the core behavioral profile is clear and additive.

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 sentences with no wasted words: the first states the action and result, the second offers usage direction. The repetition of 'public' is minor and does not harm clarity.

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 single-parameter tool with full schema coverage and no output schema, the description covers purpose, usage scope, and observable behavior. It lacks explicit failure-mode details, but nothing essential is missing for an agent to call it 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?

The input schema already fully documents the 'url' parameter with 100% coverage, including its URI format and requirement to return JSON. The description adds no parameter-level meaning beyond this, so the baseline of 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?

States a specific action ('Fetch a public http(s) URL that returns JSON') and a concrete outcome ('pretty-print it'). The mention of JSON and pretty-printing clearly differentiates it from the sibling 'fetch_url, even though that tool is not explicitly referenced.

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?

'Use for public APIs' gives clear usage context and implies this tool is not intended for authenticated or private endpoints. However, it stops short of explicitly naming the alternative sibling or stating when to choose fetch_url instead.

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