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

readOnlyHint=true already tells the agent this is a safe, non-mutating read, so the description's burden is lower. It does add useful behavioral detail: results are pre-grouped by purpose and the filter accepts partial token names, not just exact group labels. It stops short of describing pagination, output shape, or error behavior for unknown filters.

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 sentences, both front-loaded: the first establishes what the tool returns, the second establishes how to narrow it. No filler, no redundancy with the title. Appropriate for a simple single-parameter read tool.

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 read-only, one-optional-parameter tool with no output schema, the description covers the resource, its grouping, and the filter semantics well. It could say a bit more about the shape of an individual token or what happens when the filter matches nothing, but nothing essential to invoking 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% and the schema already gives example values for 'group'. The description goes beyond the schema by clarifying that the filter also matches 'part of a token name', a substring-matching semantic the schema does not state. That is genuine added meaning over the structured field.

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 names the concrete resource ('--ml-* tokens') and enumerates the purposes they are grouped by (spacing, color, type, depth, motion, etc.), so an agent knows exactly what comes back. It does not explicitly contrast itself with siblings like search_components or get_design_rules, but a read of the resource name makes the distinction obvious.

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 second sentence ('Filter with a group name or part of a token name') gives clear guidance on how to narrow results, which is real usage direction. However, there is no statement of when to prefer this tool over siblings such as search_components or get_design_rules, and no exclusions. Usage is implied rather than specified.

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