upsert_message_variant

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

No annotations are provided, so the description carries the full burden. It transparently explains idempotency, the effect of archived=true, and the 400 refusal on exceeding the cap. It does not cover authentication or rate limits, but the core side effects are disclosed well.

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 two sentences, front-loaded with the core action, and every sentence adds essential behavioral information (idempotency, archival semantics, cap enforcement). No redundancy or fluff.

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 no output schema or annotations, the description covers key behavioral aspects: idempotent updates, archived state handling, and 400 on cap. It lacks explicit mention of return values or authentication/rate limits, but for an upsert tool with rich parameter descriptions, it is sufficiently complete. Minor gap: no explicit 'when to use' exclusions, but the CRUD context is clear.

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 83% (5 of 6 properties have descriptions), so the schema already documents each parameter. The description adds broader context (how archived affects rotation, why some params are null, the purpose of bodyApproach), though it doesn't detail each parameter beyond 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?

The description clearly states the tool's function: 'Register or update a message-angle variant' with specifics on idempotency, archived state, and cap enforcement. It distinguishes itself from sibling tools like list_message_variants and pick_message_variants by focusing on creation/update behavior.

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 provides clear context on when to use the tool (when registering or updating a variant) and explains the 400 error condition for cap violations, but does not explicitly contrast with alternatives like pick_message_variant or when not to use it. It gives enough behavioral guidance for an agent to select appropriately.

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