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

The description adds genuinely valuable cost context ('Spends that endpoint's credits') that annotations do not convey, and openWorldHint already signals the arbitrary-external-call nature. However, it says nothing about per-endpoint credit costs, error behavior for invalid paths, rate limits, or whether a failed call still charges credits. Note a mild tension: readOnlyHint=true sits uneasily with a tool that consumes paid credits, though the data itself is only read.

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 action and immediately followed by the cost warning that matters most. Minimal but slightly under-specified rather than padded.

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 generic router with a fully opaque parameter object, no output schema, and real credit cost, the description leaves critical gaps: how to discover valid paths, how params map to endpoints, and what a call returns or costs. It is adequate as a hint, not as an operating manual.

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 coverage is 0% with an opaque 'params' object (additionalProperties, no properties), so the description must carry the burden. It only supplies an example path format; 'with its params' merely restates the schema field name and gives no clue how params must be shaped to match the target endpoint.

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: 'Call any endpoint by path', with a concrete example path (/v1/reddit/subreddit). It is clear this is a generic escape hatch relative to the ~70 named sibling tools, though it never says that explicitly.

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?

No guidance on when to use this instead of the many dedicated siblings (twitter_tweet, youtube_video, etc.) or when it is inappropriate. It also omits the obvious prerequisite that a valid path must first be discovered, presumably via the sibling list_endpoints.

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