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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), yet the description adds substantial behavior: the tool is free, a run requires prepaid credit >= estimated max cost, provenance.verified=false means an expected-but-unverified shape, credential semantics ('platform_own_key_optional'), and that workflow ids are accepted. This is rich context well beyond the 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?

The core purpose is front-loaded, which is good, but the rest is a single dense paragraph of run-on sentences with nested parentheticals and quoted field names. Several clauses are repetitive (endpoint.capability/sourceCapability/credential definitions, detail='run' field list) and could be trimmed or bulleted.

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?

With no output schema, the description does the work of explaining return content: schema, price formula, estimatedMaxCost, provider identity, provenance.verified, and the detail='run' reduced payload. It covers a complex tool well, though the sheer density means some structure (e.g. field grouping) is left to inference.

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 0%, so the description carries the burden and largely does: it fully explains the 'detail' enum ('run' returns only run-necessary fields plus a run template; 'full' is unchanged) and clarifies endpointId can be a workflow id (CA-WF-02/08). The endpointId format is only loosely specified, keeping it from a 5.

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 opening states a specific verb and resource: 'inspect a data API endpoint (free)' returning its schema, price formula, max cost and provider identity. It also distinguishes itself from the sibling 'run' by framing inspection as the step done 'before running it.' It stops short of explicitly naming alternatives like discover/search_catalog for finding endpoint ids, which keeps it out of 5 territory.

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 gives concrete context: use this before a run to see requirements, and note that a run needs prepaid credit >= estimated max cost. It also explains when to pick detail='run' vs the default 'full', which is genuine selection guidance. No explicit when-not or named sibling alternatives, so not a 5.

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