Root cause

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

Annotations only declare the safety profile (readOnly, idempotent, non-destructive, openWorld); the description goes well beyond that by disclosing the comparison-against-baseline method, millisecond-level error pinning, deploy/restart/host-rollout detection, call-graph inference from traces, and the ranked-verdict-with-timeline output shape. That is substantive behavioral context an agent cannot get from structured fields.

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?

The core purpose is front-loaded in the first clause, the middle enumerates only capabilities that actually differentiate the tool, and the final short sentence gives the usage cue. No sentence is padding.

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 must carry return-value semantics, and it does ('returns a ranked verdict with a timeline and evidence'). All 7 optional parameters are schema-documented, and the description supplies the analytical context an agent needs to call this correctly for incident triage.

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 description coverage is 100%, so the baseline for parameter understanding is already met by the schema itself. The description alludes to the baseline-comparison concept, which lightly reinforces the 'baseline' parameter, but adds no syntax, format, or defaulting detail beyond what the schema already documents.

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?

Opens with a specific, high-signal statement of the job ('Find which service broke first and why') and then enumerates the concrete analytical steps it performs. An agent can distinguish it from error_summary, trace_request, and service_map because it explicitly fuses error, traffic, latency, deploy, and trace analysis into one ranked verdict.

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 closing line 'Start here for "what is causing this incident?"' gives a clear routing condition and makes this the default entry point for incident triage. It does not name sibling alternatives (e.g. error_summary or trace_request) or state when NOT to use it, so it falls short of full when/when-not guidance.

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