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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so safety is covered. The description adds real context beyond that: the response embeds the last 20 changes with before/after snapshots plus recent checks, which tells the agent this call is heavier than a bare metadata read.

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 sentence, zero filler, and the most decision-relevant fact (the 20-change and checks payload) is front-loaded.

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?

No output schema exists, so the description must sketch the return value, and it does: the watch, its last 20 changes with before/after, and recent checks. It leaves out what happens if the id is unknown or whether the change list is truncated beyond 20, which are minor for a read-only getter.

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?

There is a single required parameter with 100% schema description coverage, and the schema itself points to list_watches as the id source. The description adds nothing about the id format or failure behavior, so baseline 3 applies.

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 names the resource (a single watch) and enumerates what comes back with it: the last 20 changes with before/after values and its recent checks. That is concrete and distinguishable from the sibling list_watches, though the retrieval verb itself is only implied by 'One watch'.

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?

Using 'One watch' against the sibling list_watches implies this is the single-record fetch, but the description never states when to choose it over list_watches or the change/check listing tools. Usage is inferable rather than explicit.

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