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

Annotations already declare readOnlyHint=true and openWorldHint=false, but the description adds two behavioral facts the annotations do not: the call is free and requires no API key. That is real cost/auth context an agent needs when deciding whether to probe first. It stops short of describing pagination or rate limits, which keeps it from a 5.

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 short sentences, front-loaded with what is returned, then when to call, then cost. No sentence is redundant 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?

There is no output schema, so the description carries the burden of describing return values — and it does, listing every field an agent would need to construct a follow-up call_endpoint invocation. Combined with the cost/auth note, nothing material is missing for this simple single-argument tool.

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?

With a single parameter at 100% schema description coverage, the schema already explains that 'endpoint' is an ID sourced from search_endpoints with an example format. The description contributes nothing further about the argument's syntax or edge cases, so the baseline 3 applies.

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 ('Get the full parameter list for one endpoint') and then enumerates exactly what comes back: name, type, required flag, allowed values and limits, example params, credit cost, tier. An agent can distinguish this read-only introspection tool from call_endpoint and search_endpoints 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?

'Call this before call_endpoint unless you already know the parameters' gives both the recommended sequencing and the explicit exception that skips it. The alternative (call_endpoint) is named directly, so routing is unambiguous.

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