co_select_variants

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

The annotations (readOnlyHint=false, destructiveHint=true, idempotentHint=true) indicate a mutating selection operation. The description adds the crucial clarification that only view state changes and no image data/metadata/library is modified, which meaningfully tempers the destructive hint. It does not detail side effects of replace/add/remove beyond the schema, but the disclosure is solid. No contradiction with annotations.

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?

Three sentences, all dense with meaning: purpose, behavioral qualifier, and use cases. No filler or repetition. The key constraint (view state, non-destructive to data) is front-loaded near the verb.

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?

The description covers purpose, side effects, and likely usage intents. With no output schema, a tool that mutates selection state needs to clarify what happens and what doesn't; it does. It doesn't mention how selection interacts with the current document/collection context, but that's inferable from sibling names and the variant_ids parameter.

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 clear per-parameter descriptions ('Variant ids from co_list_variants', mode enum with 'replace, add, remove'). The description adds no parameter-level detail beyond the schema, so baseline 3 is appropriate.

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?

Clearly states the action ('Change which variants are selected'), the target system ('in Capture One'), and immediately distinguishes it from data-modifying operations ('Selection is view state — no image data, metadata or library structure is modified'). This is a specific verb+resource description that leaves no ambiguity about what the tool does.

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?

Provides concrete use cases ('stage a set for the user to look at', 'set up a subsequent selection-scoped call'), giving clear context for when to invoke it. It does not explicitly name sibling alternatives or when not to use it, which prevents a 5.

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