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

No annotations exist, so the description carries the full burden, and it does add real value by disclosing the price and payment mechanism ('0.001 USDC per call via x402'), which the schema only hints at via the paymentProof parameter. It does not disclose output shape when a wildcard matches many nodes, nor behaviour on invalid JSON or an unmatched path, which are significant gaps for an annotation-free tool.

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 short sentences, front-loaded with the core action and followed by the cost constraint. Nothing is wasted and nothing is buried.

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 tool with no annotations and no output schema, the definition should pin down what 'returns the matches' means (array of values, array of objects, first match) and how payment retries behave. The payment loop is covered by the schema's paymentProof description, but the return shape for multi-match paths is left ambiguous.

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 all three parameters are documented, giving a baseline of 3. The description's path examples add a little meaning ('items[*].id' shows wildcard projection) beyond the schema's single example, but it says nothing about the json or paymentProof parameters that the schema does not already state.

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 and resource ('Evaluates a dot/bracket path ... against JSON and returns the matches') and supplies two concrete path examples, so the agent immediately knows this is JSONPath-style extraction rather than formatting. It does not explicitly distinguish itself from the sibling json_format, which is the main thing holding it below a 5.

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 implies usage through examples (data.items[0].name, items[*].id) but never says when to pick this over json_format or what happens when the path matches nothing. There is no explicit when-to-use or when-not-to-use guidance.

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