tokmeter_cache_efficiency

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

The readOnlyHint and openWorldHint annotations already communicate the safety profile, so the description does not need to restate that. It adds useful behavioral context by describing the returned analysis: hit rate, dollar savings, cache write waste, and per-model breakdown. It does not cover permissions or rate limits, but those are less critical for this read-only analytics tool.

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 three sentences, front-loaded with the core action and followed by the output contents and intended use. Every sentence contributes useful information with no 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 low-complexity, read-only analytics tool with fully documented optional parameters and no output schema, the description is largely complete: it states the analysis and the key return categories. Minor details such as default period behavior are left to the schema, but nothing essential is missing.

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 all three parameters (period, project, provider) are already documented in the schema. The description does not add parameter-level meaning beyond the output categories, so the baseline score of 3 is appropriate.

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 gives a specific verb and resource: 'Analyze cache hit/miss patterns across sessions.' It also enumerates the key outputs (hit rate, dollar savings, write waste, per-model breakdown), making the tool's purpose clear. It does not explicitly distinguish itself from sibling tools such as tokmeter_efficiency, which keeps it from a 5.

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 sentence 'Use this to understand how effectively prompt caching is reducing your costs' gives clear contextual guidance for when to invoke the tool. However, it does not mention when not to use it or name alternative sibling tools, so it falls short of full when/when-not/alternatives guidance.

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