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

Annotations already declare this is a non-destructive, idempotent mutation, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: it states the tool returns the variant as it now stands and advises confirming the change via the response rather than assuming success.

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?

Two tight sentences, front-loaded with the mutation surface followed by the return-value guidance. No filler, no redundancy.

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 explains what comes back and that the caller should verify it, and the schema fully documents the nested inputs. It omits any note on permissions or the participants-replacement caveat (which lives only in the schema), so it is strong but not exhaustive.

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%, and the nested data object already documents each field, including the exact-vs-flexi date structures and the replace-whole-structure semantics for participants. The description's 'exact dates or a flexible window' phrasing mirrors what the schema already states, so it adds little beyond the 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 and enumerates the exact editable fields (name, dates, notes, participants), so an agent knows precisely what it mutates. It does not, however, distinguish itself from close siblings like create_variant, duplicate_variant, or select_variant, leaving that inference to the agent.

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?

Usage is implied by the field list ('Rename a variant, change its dates...'), but there is no explicit when-to-use guidance, no exclusions, and no routing to alternatives such as duplicate_variant or select_variant. The only operative advice is to read the response to confirm the change.

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