index

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

With no annotations, the description carries the full burden and does disclose persistence location, the environment flag that bypasses it, and that index_clear destroys cached data. It stops short of describing build cost, permissions, or concurrency behavior, but the safety-relevant traits (opt-in, destructive clear) are present.

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?

A single dense paragraph that front-loads the resource definition and then maps each action to its effect. Nearly every clause earns its place, though the trailing action list slightly duplicates the schema enum.

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 multiplexed cache tool with no output schema, the description covers what the cache is, where it lives, each action's effect, and its optionality. It does not sketch the shape of index_status output beyond 'what is cached and how old it is,' which is a minor gap.

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 100%, so the schema baseline is 3, but the description adds meaning the schema lacks by naming the per-action args (filepath, with_transcript) and tying index_build to a timeline source. This goes beyond restating the generic action/args structure.

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 opens by naming the resource concretely (the analysis cache at ~/.fcp-mcp/index.db) and enumerates the three sub-actions the tool dispatches. It distinguishes itself from siblings by stating that every other tool works with the index off, though the top-level verb 'index' alone would not convey this.

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?

Each action is paired with its role: index_status reports cache contents/age, index_build warms it for every source in a timeline, index_clear drops it. It also gives an explicit when-not by noting the index is optional (FCP_MCP_INDEX=off) and that it only speeds up the second question, which tells the agent not to treat this as mandatory.

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