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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds a genuinely useful non-annotation detail: the call requires an x-api-key. It stops short of describing return shape, pagination, or ordering, but that is a modest gap given the annotation coverage.

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 short sentences with zero filler; the core purpose is front-loaded and the auth prerequisite follows. Nothing redundant with the title or annotations beyond the necessary auth note.

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 parameters, no output schema and rich annotations, the description covers what the tool returns (active watches) and what it needs (an API key). Only minor gaps remain, such as whether inactive watches are excluded or how results are ordered.

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 tool takes zero parameters, so the schema carries no semantics to explain and the baseline is 4. The description correctly implies the result set is scoped implicitly by the caller's API key rather than by any argument.

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 ('List') and resource ('active per-server watches for this API key'), which is enough to separate it from the watch_subscribe and watch_unsubscribe siblings. It does not name those siblings explicitly, so differentiation relies on the verb alone.

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?

Usage is only implied: an agent can infer this is the read-side counterpart to census_watch_subscribe / census_watch_unsubscribe. There is no explicit statement of when to call this versus those alternatives, and no note about when a listing would be empty or when another tool should be preferred.

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