prune_store

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

Clarifies that only local history cache is deleted, not messages from Signal servers. Discloses non-destructive behavior toward server data. Lacks details on reversibility or performance impact, but sufficient given no annotations.

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 sentences, no filler. First sentence states action and default; second clarifies scope and use case.

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 one-parameter tool with no output schema, description fully explains what it does, what it doesn't do, and why to use it.

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?

Only one parameter 'days' with schema description already stating 'Delete messages older than this many days (default: 180)'. Description adds no additional meaning beyond schema, so baseline score.

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?

Clearly states verb 'Delete', resource 'locally stored messages', and scope 'older than a given number of days' with default. Distinguishes from siblings like 'clear_local_store' and 'delete_local_messages' by specifying age-based filtering.

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?

Provides guidance: 'Useful for keeping the store from growing unbounded.' Does not explicitly mention when not to use or alternatives, but usage context is implied.

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