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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds behavior beyond them: it names the returned payload (source text plus citation URL) and discloses a real quirk, that device results are truncated to the first 20 mods with get_device for paging.

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 short sentences, front-loaded with the action and then the ID format, with zero filler. The pagination caveat is placed last where it belongs as a follow-up consideration.

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?

An output schema exists, so return values need not be enumerated in depth, and the description still summarizes them plus the device-truncation caveat. The only meaningful omission is guidance on fetch versus get_mod for retrieving a single mod, which matters given how many get_* siblings exist.

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 0%, so the description must carry the single parameter, and it does: it explains that the ID must be the exact prefixed form and supplies device:whoop and mod:open-health as models of the required pattern. It omits the maxLength and minLength bounds, but those are enforced by the schema itself.

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 ("Read a device or mod") and scopes it to records "found by search," which separates it from the listing/search siblings. The two prefixed-ID examples make the resource type concrete enough that an agent can identify the call 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?

Gives clear when-to-use context (records already located via search) and an explicit alternative for one case: "use get_device for further pages" when a device returns only 20 mods. It does not address when to prefer this generic fetch over the sibling get_mod for a single mod record, leaving one routing decision to inference.

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