cache_stats

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

No annotations are provided, so the description carries the full burden. It states the tool 'returns' statistics, implying a read-only operation with no side effects, but it does not explicitly affirm that it does not modify the cache, nor does it mention any access requirements or potential large payloads. The listed return fields add transparency, but the lack of explicit behavioral caveats keeps this at a passing but not exceptional level.

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 a single, efficient sentence that front-loads the core purpose and then lists the specific statistics returned. Every word contributes value; there is no redundancy or filler.

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?

Given the tool's simplicity (zero parameters, no annotations) and the presence of an output schema (which likely documents the return format), the description covers the essential behavior. It could be slightly more complete by explicitly stating that this is a read-only inspection and noting any prerequisites, but nothing critical 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?

The input schema is empty (0 parameters), so there are no parameters to describe. Per the rubric, a zero-parameter tool gets a baseline of 4. The description adds no parameter information because none exists, which 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 clearly specifies a verb ('return') and a resource ('cache statistics'), and enumerates exactly what is returned (entry count, total size, TTL, limits). It is unambiguously distinct from sibling tools like web_search or cache_clear, which are about web operations or cache clearing.

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 indicates the tool is for inspecting cache state, which provides clear context for when to use it (when cache statistics are needed). However, it does not explicitly mention alternatives or exclusions, though the distinct resource and zero parameters make usage fairly obvious without further guidance.

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