upsert_canonical_api_definition

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

With no annotations, the description carries the full burden and does so well: it discloses that writes are previewed by default (dryRun true returns `preview`), that a write requires both dryRun=false and confirm=true, that the replace is atomic with an optional .bak backup, and that endpoint ids must not collide on append. These are exactly the safety/mutation traits an agent needs.

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?

Dense and front-loaded: the core action leads, followed by mode requirements and then the write-safety workflow. Telegraphic but every clause conveys a distinct constraint; nothing is wasted.

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 an 8-parameter mutation tool with nested objects and no output schema, the description covers the write semantics and mode conditions thoroughly. Minor gaps remain around the shape of the `preview` return and workspaceRoot fallback, but the essentials for correct invocation are present.

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?

At 50% schema coverage, the description adds real conditional meaning beyond the schema: replace_file requires replaceDefinition, append_endpoints requires appendEndpoints, and a missing file on append requires createIfMissing. This cross-parameter dependency mapping is the key value-add, though targetRelativePath and workspaceRoot are left to the schema.

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+resource ('Create or update a canonical YAML') and bounds it to `.mcp/api/`, which is precise enough to separate it from read/list siblings. It does not, however, name or distinguish itself from the other definition-writing siblings like convert_legacy_to_canonical or import_curl.

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 gives strong operational guidance for how to use the tool (which mergeMode requires which payload, the dryRun/confirm workflow), but it never states when to reach for this tool versus the sibling converters/importers. Usage is implied by the create/update scope rather than contrasted with alternatives.

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