cost_summary

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

No annotations provided, so the description carries full burden. It discloses the output metrics but does not state behavioral traits like read-only nature, side effects, authentication needs, or whether data is aggregated or real-time. More transparency is needed.

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?

Single sentence, front-loaded with main purpose, no wasted words. Every part is informative.

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 no output schema, the description adequately covers what the tool returns. It mentions key metrics and filtering by project. Could explicitly state the return format or that it's a summary object, but overall sufficient.

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 0% (no parameter descriptions). The description hints at project filtering ('top projects') and time scope ('across'), but does not explicitly explain 'days' parameter meaning or default behavior. It adds some value but is incomplete.

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 the tool provides a token cost summary across Claude Code projects, listing specific metrics (output/input tokens, cache hit rate, estimated dollars, top projects and tools). This distinguishes it from siblings like audit_summary and efficiency_report.

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?

Usage is implied for cost analysis, but no explicit guidance on when to use this versus sibling tools (audit_summary, efficiency_report, safety_report). The description lacks when-not-to-use or alternative recommendations.

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