list_variants

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

With no annotations provided, the description fully carries the transparency burden. It discloses the read-only nature, shows actual indexed state versus config, and describes the output structure including behavior for single-project indexes. It also clarifies the 'authoritative per-build state' aspect.

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 concise and well-structured: a one-sentence purpose, a clarifying behavioral note, and a usage comparison. Every sentence adds value without 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?

Given the simple single-optional-parameter tool with no output schema or annotations, the description is complete. It covers the output format, edge case (single-project), and relationship to sibling tools, enabling correct selection and invocation.

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?

The only parameter, project_root, is already described in the schema with 100% coverage ('Auto-detected from CWD if omitted'). The description does not add parameter-specific details, so the 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?

The description opens with 'List every indexed build with its (variant, image, board) identity', using a specific verb and resource. It clearly distinguishes this tool from siblings like get_active_build by focusing on per-build config_hash and symbol counts.

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 explicitly states when to use this tool versus get_active_build: 'Use get_active_build for the mandatory first-call health check... use this tool to see the per-build config_hash and symbol counts.' It also clarifies that this is a read-only diagnostic, giving a clear alternative.

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