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

Annotations already cover readOnly, idempotent, non-destructive, closed-world, so the description only needs to add context. It does: it discloses ordering ('newest first'), account-wide scope, and the shape of each returned change row — meaningful detail given there is no output schema.

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: the first front-loads scope, ordering and return shape, the second gives the use case. Nothing is redundant or buried.

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 compensates by enumerating the returned fields and ordering. Minor gaps remain: no mention of result caps/pagination or whether empty results are possible, but an agent has enough to call it correctly.

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?

Only one parameter with 100% schema description coverage, including the RFC 3339 format and the 7-day default. The description's 'since a moment' merely restates the parameter name without adding format or edge-case detail, 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 states a specific verb+resource ('the changes on all of the account's watches'), plus ordering ('newest first') and the returned fields ('which watch, when, before and after'). It implicitly distinguishes itself from per-watch siblings like get_watch and list_watches by scoping to ALL watches, though it never names them.

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?

'Use it to answer what changed lately' gives an implied usage context, but there is no explicit when-not condition and no alternative tool is named (e.g. get_watch for a single watch's current state). Guidance is present but thin.

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