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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description adds real value by saying it is an instant archive read with no LLM cost and by disclosing the default window and the degraded-fewer-than-two-snapshots behavior. It does not discuss permissions or rate limits, but those are implied by the read-only annotation.

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?

Three short sentences, front-loaded with what is compared, then latency/cost, then default and edge case. No filler.

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 return-shape burden and does well: theme labels, percentage-point deltas, and the note case. It omits how many themes are returned or ordering, a minor gap for a comparison tool.

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 coverage is 100%, so the schema already documents appId, from, to and store with examples. The description only adds the default from/to window, which is useful but does not go beyond what the schema's 'optional, default newest' already implies.

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?

Specific verb and resource: it compares two archived analyses and labels each theme new/resolved/rising/falling/stable. That clearly separates it from mine_app_pain_points (which produces the analyses) and from get_app_reviews, so an agent can pick it without opening the schema.

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?

Gives the default comparison window (latest vs ~30 days earlier) and states what happens when the precondition fails ('fewer than two snapshots'), which is the key when-to-call context. It stops short of naming the sibling to use instead when there aren't two snapshots.

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