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

Annotations already mark destructiveHint=true, readOnlyHint=false, and idempotentHint=true. The description adds behavioral context beyond that by mentioning the route identity matching (prefix or regex), the requirement for workloadLink, the optional omission of matchers to match '/', and the return of the full updated domain JSON. This complements the annotations without contradiction.

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 description is three sentences, front-loaded with the primary action, and every sentence is purposeful. It includes a useful pointer to the runbook without unnecessary embellishment. No redundancy or 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?

Given the complex nested schema (5 required params, nested objects, 100% coverage) and the indication of an output schema, the description covers the essential workflow: identify, replace, and inspect result. It directs to the runbook for deeper context. It doesn't enumerate edge cases, but the schema does, so it's adequately complete.

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% with detailed descriptions for every parameter, including routeIdentifier and route. The description adds some semantic gloss (e.g., 'whichever it uses' for route matcher, 'may omit optional matchers to match /') but does not significantly extend the schema's own documentation. Baseline 3 is appropriate given the high schema coverage.

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 uses a specific verb ('Replace') and resource ('single route entry on a port listener'), clearly distinguishing this update tool from sibling add_domain_route and remove_domain_route. It also explains the core mechanics (identify via prefix/regex, require workloadLink) which further pins down the purpose.

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 description clearly indicates when to use the tool (replacing an existing route) and provides context about identifying the route and required fields. It does not explicitly name alternatives or state exclusions, but the replace vs. add/remove distinction is implicit. The recommendation to read get_cpln_skill before first use is a useful usage guideline.

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