Item (read)

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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered; the description adds value by disclosing the return shape per action (timing, source range, track, flags, links; take count and selected index; whether the timeline blanking is used). It does not cover pagination or error behavior, but for a read-only tool this is well above the annotation bar.

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?

One purpose sentence up front, then a scannable action list with a legend for the '*' required marker. No filler; every line carries an action name, its parameter, and its return 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?

Given a nested polymorphic input, annotations covering safety, and an existing output schema, the description supplies the missing piece (action catalog with per-action params and return hints) and routes the agent to describe_action for deeper detail. Nothing needed to invoke it correctly is absent.

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?

The schema is a generic nested object with additionalProperties and only names the enum values, so the description is the sole source of action-level parameter semantics — and it delivers, marking `item` as required per action and explaining what each action reads. This is exactly the compensation the schema needs.

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 a specific verb+resource and a scope constraint ('Read item state, no side effects'), then enumerates every supported action. An agent can distinguish this from item_write / item_delete purely from the description, and each action name is paired with what it returns.

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 a light use case ('use it to find ids and check results') and points to describe_action for per-action parameters, but never states when not to use it or how it relates to siblings like timeline_read, media_read, or item_write. Usage is implied rather than directed.

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