Diagnose a missing or unplayable item

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

Beyond the readOnlyHint annotation it discloses non-obvious behaviour: the ordered check chain, the cross-service fallback for titles no longer in the library, the `certain: false` marker when a step could not be checked, and service-specific extras (Reclaimerr deletion verdicts, Bazarr subtitle notes, Lidarr artist semantics). The explicit statement that it never executes `next_steps` resolves the main ambiguity an agent could have about a read-only tool that emits remediations.

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?

Front-loaded with the question the tool answers, then progressively narrower detail. It is dense and every clause carries information, but the long compound sentence with the parenthesised chain and the field reference at the end is heavy to parse. Slight trimming would improve scanability without losing content.

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 multi-backend diagnosis tool with an output schema, the description covers the check ordering, fallbacks, uncertainty signalling and the key return fields (`remedy`, `next_steps`, `certain`) that drive how the agent should respond. Nothing needed to call it correctly or interpret a 'could not check' result 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 80%, so the schema already documents `user`, `service`, `instance` and `query` reasonably. The description adds real meaning for `query` (a human-style title rather than a slug) and the `service`+`id` pairing, but says nothing about the `user` parameter or the `allow_other_users` gate, leaving that entirely to the schema.

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?

Opens with the concrete user question ("Why is this not playable?") and states a specific mechanism: walks the chain from requested through scanned and names the first failing link with a remedy. That is clearly distinguishable from the sibling getters (get_queue, get_history, get_wanted) and from action tools like trigger_search.

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?

Gives explicit invocation shapes: a title via `query`, or `service` plus `id` when an exact item is in hand, and notes the title falls back to Cleanuparr, download-client history and the event log. It also impliedly draws the boundary from action tools by saying it never runs the suggested steps. It stops short of naming a sibling as an alternative or an explicit when-not-to-use case.

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