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

Annotations already declare readOnly, idempotent, non-destructive behavior, so the safety profile is covered. The description adds two genuinely useful behavioral facts beyond that: the return set is bounded to the last 20 evidence_event ids, and credential hashes are never returned — a meaningful security disclosure.

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?

Two dense sentences with zero filler; the verb and lookup key are front-loaded and the returned-field inventory follows immediately. Nothing is repeated from the schema or annotations.

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?

With no output schema, the description carries the burden of describing the return payload and does so explicitly, including the 20-event cap and the credential-hash exclusion. An agent knows what it will receive before calling.

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% for the single device_id parameter, so the schema already documents it. The description adds only the trivial clarification that lookup is by id, which is the baseline 3 when the schema does the heavy lifting.

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 ('Get one device by id') and then enumerates exactly what the response contains (kind, name, status, zone, rotation timestamps, revocation reason, last 20 evidence_event ids). The singular 'one device' also implicitly separates it from the sibling tascan_list_devices.

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?

The phrase 'by id' implies this is the point-lookup counterpart to the list operation, which is enough to infer intended usage. However, it never names tascan_list_devices as the alternative or states when not to use it, so the routing guidance is only implied.

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