usage_summary

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

Without annotations, the description carries the full burden and discloses key behavioral traits: it reads local data and never touches vendor APIs, indicating a safe, read-only operation. However, it does not mention or confirm other aspects like whether it modifies data or performance implications.

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?

The description is two sentences, front-loaded with the key action ('Quick spend + token summary'), and every sentence provides useful information without redundancy.

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 simple tool with one optional parameter and no output schema, the description covers the core purpose, data source, and safety (local only). It is complete enough for this complexity, though it could benefit from mentioning the output format in more detail.

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?

With 0% schema description coverage, the description should compensate but only vaguely mentions 'over a period'. The input schema itself provides clear enum values and default, so the parameter meaning is clear, but the description adds minimal additional value beyond that.

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 clearly states what the tool does: provides a quick summary of spend and tokens for Claude Code and Codex over a specified period. It also distinguishes itself from siblings by specifying it reads local Token Meter data and never touches vendor APIs.

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 implies when to use the tool (for local data summaries) and hints at alternatives (since it doesn't touch vendor APIs, it's not for real-time vendor data), but it lacks explicit when-to-use or when-not-to-use statements or direct comparisons to sibling tools.

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