fable_prune

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

No annotations exist, so description carries full burden. It discloses key behaviors: creates a vault backup before pruning, atomic and append-safe rewrite, and returns a resume command. Could elaborate on vault mechanism but sufficient for agent understanding.

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?

Extremely concise: two sentences covering purpose, usage, and post-instructions. Front-loaded with action and key details. No redundant phrases.

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 2-param no-output tool, the description covers what it does, when to use it, and the backup behavior. Missing details on output format (the resume command) and vault backup mechanics. Good but not exhaustive.

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 50% with session_id described well (atomic, append-safe). The description adds context that strip_images removes images, tying the boolean parameter to the stated goal of slimming. Adds value beyond schema by explaining the backup and atomicity.

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 prunes a session transcript by removing tool noise, images, and bloat. The verb 'prune' is specific and distinct from sibling tools (e.g., fable_recall, fable_block), making it easy for an agent to select this tool.

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?

Explicitly says 'Use when the user asks to prune/slim a session or complains about context size.' It also gives post-usage instructions (tell user to /exit and run resume command). Lacks when-not-to-use or alternatives, but provides clear context.

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