vizcharter_themes

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions that validation checks against 'the token schema including WCAG contrast expectations', which is a useful detail. However, it doesn't explicitly state that the tool is read-only (though 'list' and 'validate' imply non-mutating actions) or describe the return format of validation results. There is no mention of side effects, error behavior, or prerequisites beyond the default base theme.

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 a single, well-structured sentence that front-loads the primary purpose ('List built-in themes') and then clearly explains the alternative validation mode with a conditional. Every word earns its place — no fluff, no repetition.

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 tool's simplicity (2 optional parameters, no output schema), the description covers the core functionality well. However, it does not explain what the return value looks like for either mode (e.g., a list of theme names, a validation report). For a validation tool, agents would benefit from knowing whether results are a simple pass/fail or include detailed errors. The absence of any return-format guidance is a gap, but the tool is straightforward enough that this isn't severely limiting.

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 input schema covers both parameters with descriptive text (base has a default, overrides is described as 'Theme overrides to validate'), so baseline is 3 given 100% schema coverage. The description adds a key semantic detail: validation includes 'WCAG contrast expectations', which is not in the schema. It also explicitly ties `overrides` to the validation mode, but doesn't add anything about `base` beyond what the schema states.

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 states two specific actions (list and validate) on a specific resource (themes), and clearly distinguishes from siblings like vizcharter_create or vizcharter_export by focusing solely on themes. The conditional guidance for passing `overrides` makes the behavior unambiguous.

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?

It explicitly tells the agent when to use this tool: to list built-in themes or validate custom overrides. It also implies that validation is conditional on passing `overrides`. It doesn't explicitly say when not to use it, but the sibling tool names (create, update, export, icons, templates) make the domain separation clear, so an agent can infer this is the theme-specific tool.

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