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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds the aggregation scope ('across all diagnosed runs', 'fleet-level'), which is useful, but the rest enumerates return contents rather than behavioral traits like auth needs or rate limits.

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 sentences, front-loaded with the core purpose, then output contents, then usage cues. The output enumeration is a list but each item is informative and none is redundant.

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 usefully describes what the aggregation returns (failure distribution, root causes, agent-type breakdown, suggestions), which compensates for the missing schema. Purpose, scope, and usage are all present; minor gaps only around sibling disambiguation.

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% — agentId and the superadmin-only customerId are both documented in the schema, so the description need not restate them. It adds no parameter syntax or semantics beyond that baseline.

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 ('Get fleet-level step failure patterns across all diagnosed runs for an agent'), with an explicit scope that contrasts with single-run diagnosis tools. It does not name a sibling such as get_run_step_diagnosis or get_worst_run, so differentiation is implied by scope rather than stated.

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 concrete selection context via example questions ('what are my top failure patterns?', 'which agent steps are causing the most failures?'), which tells the agent when this tool applies. It stops short of naming alternatives or when-not-to-use conditions (e.g., single-run diagnosis).

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