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

Annotations already declare read-only, idempotent, open-world, non-destructive behavior, so the bar is lower; the description still adds real value by flagging determinism, the 'interpretive signals, not proof or canon' caveat, and that no authentication is required. It does not describe the return format, which is the remaining gap.

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?

Four terse sentences, front-loaded with the core action, then the interpretive caveat, then routing. Every sentence earns its place 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 one-param, read-only tool with no output schema, the description covers purpose, caveats, auth, and alternatives adequately. It could do slightly more to set expectations about the match results returned, but nothing needed to call it correctly 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% and the single 'text' parameter is fully documented in the schema (1–2000 chars, private-manuscript warning). The description's 'caller-supplied text' adds no syntax or constraint beyond what the schema already provides, so the baseline 3 applies.

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?

States a specific verb and resource (deterministic theme/phrase matching on caller-supplied text against the public pattern set) and distinguishes itself from siblings by naming search_cassie_hour_fragments and search_public_story_records. An agent can identify the operation without opening the schema.

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 routes to alternatives with their selecting conditions ('use search_cassie_hour_fragments for source essays or search_public_story_records for recorded events'). The positive when-to-use condition (when you have caller-supplied text) is implied rather than stated, so it stops short of a 5.

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