Get theme variables

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

Annotations already cover read-only/idempotent/non-destructive safety, and the description adds useful internals: it calls the `frontend/get_themes` WS command and looks up the name, plus an exact error shape listing available names when lookup fails. That error contract is real behavioral value beyond the annotations, though read-cost or caching behavior is not discussed.

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?

Uses labeled lines (Use when / Returns / Errors) with the core action front-loaded and no filler. Slightly more verbose than strictly needed given an output schema exists, keeping it from a 5.

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?

Covers lookup semantics, the failing-name error contract, and the return dict shape, and routes the agent against the sibling list tool. For a one-parameter read tool with full annotation coverage, nothing an agent needs to call it correctly is missing.

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 single `name` parameter and its 'matching a key in themes_list_themes' themes map' semantics are already documented. The description's 'by name' adds no syntax or format detail beyond the schema, so the 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 and resource ('Get one theme's CSS variable map by name') and immediately names the sibling it is distinct from, `themes_list_themes`. An agent can select this over the list tool without opening either schema.

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?

Explicit 'Use when' clause contrasts inspecting a single theme's variables against pulling the whole registry from `themes_list_themes`, giving both the condition and the alternative tool by name.

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