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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the bar is lower; the description adds genuinely useful context beyond them: 'Reads the map only', the paid-per-server model with a pointer to list_paid_tools, and the token-saving magnitude (70-90% fewer). It also sketches the card contents, though it omits return shape details.

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?

Four front-loaded sentences, each carrying distinct information (what it returns, why to prefer it, the optional filter, the cost/read-only note). Dense but without filler; the parenthetical list of card fields is the only slightly breathless part.

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 4-parameter read-only tool with no output schema, the description covers what the cards contain (compensating for the missing output schema), the optional tool filter, the cost model, and the read-only nature. The nested last_trip object is fully documented in the schema, so nothing critical is missing.

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 baseline is 3. The description's 'Optionally only the named tools' merely restates the schema's own description for tools, and the mention of payment lightly touches license_key. The last_trip object's rich schema text is not supplemented in the description.

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 description states a specific verb and resource: it returns one compact card per tool for a given server, containing what the tool does, its arguments (required marked *), risk level and side effects, plus a definition hash. It distinguishes itself from 'loading a server's full tool definitions' but does not explicitly differentiate itself from siblings like find_tool or preflight.

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 a clear condition and an alternative: 'Use this instead of loading a server's full tool definitions when you only need to choose a tool or prepare a call.' It also routes to list_paid_tools for the payment model. There is no explicit when-not-to-use or sibling comparison beyond the generic full-tool-list alternative.

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