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

Annotations already set readOnlyHint=true and idempotentHint=true, so the safety profile is covered. The description adds valuable behavioral context beyond that: it says the call is a 'cheap single-row read', states the return type ('raw walk row including device_id and the captured OID payload'), and defines the meaning of an empty result ('device has never been walked'). It also discloses the lack of a freshness timestamp, which is a real operational trap for an agent. These are genuine behavioral features not already in annotations.

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?

Five sentences, each earning its place: state the resource, label it cheap, give preferred alternative, describe the return and the empty case, and show an example. No fluff, and the crucial distinction from snmp_walk_run is front-loaded. Formatting is clear and readable.

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 tool with one parameter, no output schema, and complete safety annotations, the description covers everything a agent needs: what is fetched, where it is stored (tools_walks), the API path, the required permission, how to decide between it and snmp_walk_run, the meaning of an empty result, and the freshness limitation. There is no missing information for a correct call decision.

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 only parameter, device_id, is already well-described ('Device id to look up the most recent stored walk for'). The description adds an example call (snmp_walk_last({device_id: 42})) but does not add meaning beyond that. Baseline 3 is appropriate because the schema already carries the semantics and the description adds marginal color.

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?

The description opens with a precise verb and resource: 'Fetch the most recent stored SNMP walk for a device'. It names the cache table (tools_walks), the wrapped HTTP endpoint, and the permission required. It explicitly distinguishes itself from the sibling tool snmp_walk_run ('Always try this first', 'Only fall back to snmp_walk_run'), so an agent can immediately tell them apart.

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 description gives explicit guidance: always call this first for an SNMP walk, fall back to snmp_walk_run only if the cached row is missing or stale. It even explains how to assess staleness given the controller does not stamp a freshness header. This is a textbook example of when/alternatives guidance with no ambiguity.

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