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

Annotations only declare readOnlyHint=true, and the description adds real value beyond that: free tier, an explicit 5 MB cap with the failure mode ('errors on invalid JSON or over 5 MB'), and the non-obvious return shape (one match bare, several as an array). Those are exactly the traits an agent cannot infer from structured fields.

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?

All the critical facts come first — free, read-only, source exclusivity, return shape — in one tight paragraph with no filler. The density borders on cryptic in the syntax list, but nothing is wasted.

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?

There is no output schema, so the description must carry return semantics, and it does partially (match cardinality, error conditions, limit-truncation guidance lives in the schema). A brief note on the error payload shape would close the remaining gap.

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 schema already documents every parameter including the filter operators and the limit envelope. The description's main additions are negative constraints ('no slices or jq') and the 5 MB bound, which are useful but largely restate schema-level facts, so the baseline of 3 is right.

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 (JSONPath query over JSON from a URL or inline string) and pins the exact syntax subset supported. It also distinguishes itself from the paid sibling json_query_xl, so an agent can place it without opening a schema.

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?

Explicitly notes url and json are mutually exclusive ('one of the two') and names json_query_xl with its 25 MB ceiling as the alternative for larger payloads. It stops short of routing against other siblings (csv_query, fetch_extract), so it is clear but not exhaustive.

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