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

Annotations already cover read-only, idempotent, closed-world. The description adds genuinely useful context annotations don't: the call is 'Free' (no credit cost), which matters for an agent guarding spend. It doesn't discuss rate limits or error behavior, so it stays at a modest 3-4, closer to 4 but capped by limited extra disclosure.

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?

One dense sentence enumerating the return fields followed by a short usage tip; the highest-value items (what you get, that it's free) come first. No wasted phrasing.

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?

No output schema exists, so the description carries the return-value burden, and it does so by enumerating fields. Combined with a single well-documented optional param, an agent has enough to invoke it correctly; it could add the return shape (e.g. per-day granularity) but is largely complete.

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 100%, and the days parameter is fully documented with default and max in the schema. The description mirrors it ('over the last `days` days') without adding format or edge-case meaning, so 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 (show) and resource (the organization's credits) and enumerates exactly what is returned: remaining credits, expiring on renewal, daily cap and remaining today, spend and crawls per day. Easily distinguished from crawl/booking siblings.

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?

Gives concrete timing guidance — 'Use it before a long job to check it can be paid for' — which tells the agent the condition that makes this worth calling. No exclusions or named alternatives, but there is no real sibling alternative for this resource.

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