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

Annotations already declare idempotentHint=true and destructiveHint=false, so the description is not burdened with safety disclosure. It usefully explains the downstream effect (suppresses the insight from future queries for the authenticated user), but omits whether marking is reversible/unmarkable and what happens for an invalid or foreign insight_id.

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, front-loaded with the action and effect, with no filler. Slightly better than minimal, though the payoff sentence is somewhat generic.

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 one-parameter mutation with annotations covering idempotency and non-destructiveness and no output schema, the definition supplies enough to invoke it correctly. The remaining gap — behavior on invalid or non-owned insight_id — is minor.

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 parameter with 100% schema description coverage, so baseline is 3. The description adds no meaning beyond the schema — it does not clarify whether insight_id must belong to the caller or how IDs are obtained (e.g., from get-my-insights-tool).

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 and resource ('Mark a specific insight as seen') plus a scope qualifier ('by the authenticated user'), which distinguishes it from read-oriented siblings like get-my-insights-tool. It does not explicitly name or route against those siblings, keeping it just short of a 5.

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 second sentence implies when to use it — after reviewing an insight, to reduce noise in future queries — but never states when not to use it or points to an alternative tool for retrieving or dismissing insights. Usage is inferred rather than prescribed.

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