update_variant

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

Annotations already declare it non-destructive and non-readOnly, so the safety profile is covered. The description adds the valuable fact that 'History keeps the old text', disclosing that edits are versioned/recoverable - context beyond the structured fields.

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 action and the affected fields, with the history behavior appended. No waste.

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 a mutation tool whose annotations carry the safety profile, the description covers reversibility and the editable surface; the session/variant parameters are fully specified in the schema. No output schema is needed for a mutation acknowledgment.

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%, so the schema already documents all five parameters including the meaning of 'name' (tab label) and the session/variant references. The description restates the editable fields but adds no syntax or format beyond the schema. Baseline 3 applies.

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 (edit/rename) and resource (variant) plus the exact fields affected (script, name, note). Clear, though it doesn't differentiate itself from siblings like rename_take or update_session.

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 - edit or rename a variant - but there is no explicit when-to-use guidance and no routing away from the many sibling tools (e.g. rename_take, script_history) an agent might confuse it with.

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