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

Annotations already cover read-only, non-destructive, open-world, so the bar is lower; the description still adds meaningful behavior: non-owner results are scoped to the caller (`scope: "member"`), and under a spend cap the balance reflects an allowance rather than total credits. It does not explain caching or freshness, but the key semantic caveats are disclosed.

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 what the tool returns. The scope/cap clause is compact but slightly cryptic, and 'their own' is vague about what is being scoped (spend vs. calls).

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 should convey the shape of the result. It names the main values (credits, recent spend, recent calls) and the member/allowance semantics, but leaves out the spend window, units, and how 'recent calls' are represented.

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?

Zero parameters, so the baseline is 4. The description's mention of a `scope: "member"` result mode adds useful context even though it is not an input.

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 the specific resource returned: spendable credits and recent spend, scoped to this workspace. It has no explicit verb, but the resource and read intent are unambiguous and no sibling competes in the billing domain.

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?

Implied usage (check credits/spend) is clear, and the 'Free' note signals it costs no credits, but there is no explicit when-to-use or when-not guidance. The absence of any sibling billing tool makes this less harmful.

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