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

Annotations already establish readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds real behavioral context beyond that: results are scoped to the authenticated organization, exclude deleted incidents and incidents with deleted parents, resolution-time averaging looks back 30 days regardless of open date, and the mean is null when unavailable. It does not describe the shape or ordering of the returned metrics, which keeps it short of a 5.

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 sentences, front-loaded with the scope and the enumerated metrics, with the routing advice last. The middle sentence is dense with clauses but each clause (deleted-parent exclusion, 30-day lookback regardless of open date, null mean) carries information an agent would otherwise guess wrong.

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 input parameters and no output schema, the description carries the burden of explaining what comes back, and it largely does by listing the four metrics and the null-mean case. It stops short of describing the response structure or units beyond minutes for resolution time, which is a minor residual gap.

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 imposes nothing to explain and the baseline is 4. The description correctly implies no input is needed — all scoping (organization, 24-hour and 30-day windows) is fixed internally rather than parameterized.

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 a specific verb and resource ('Summarize ... incidents') and then enumerates exactly which aggregates are produced: active count from the IsActive flag, active unacknowledged, opened in the last 24 hours, and mean resolution time in minutes. That level of specificity makes it unmistakable against siblings like incident_list or incident_report.

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 final sentence routes the agent explicitly: use IncidentList for individual incidents or IncidentReport for trends. Both alternatives are named with the condition that selects them, so an agent can choose without opening other schemas.

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