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

Annotations already declare readOnlyHint=true, so the safe-read profile is covered. The description adds the underlying REST endpoint (GET /payment/usage), which is minor debugging value, but says nothing about auth scope, aggregation granularity, or whether the result is a total or a line-item breakdown. With annotations carrying safety, this is adequate but adds little.

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 purpose before the REST mapping. Nothing is wasted, though the REST endpoint line is marginal value for an agent that only needs to call the tool.

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 more burden for conveying what comes back; 'spend / usage' is thin and doesn't say whether the response is a single aggregate or a per-model/per-period breakdown. Combined with the unaddressed sibling overlap, the definition is minimum-viable rather than 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 description coverage is 100%, so the schema already documents both 'from' (formats: YYYY.MM, 'current', 'current(-N)', unix timestamp) and 'to' in detail. The description adds no parameter semantics beyond implying a billing period. Baseline 3 applies since structured data does the heavy lifting.

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 spend / usage for a billing period') with a scope qualifier, which is clearer than a bare 'get usage'. However, it does not differentiate itself from the close siblings deepinfra_get_usage_rent and deepinfra_get_usage_tokens, so an agent cannot tell from the text alone whether this is the aggregate billing view or a subset.

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?

The description gives no when-to-use context, no prerequisites (e.g. billing/account scope), and no routing advice toward the rent/tokens usage siblings. The agent must infer usage from the name alone.

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