List local components

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

Annotations already cover the safety profile (readOnly, non-destructive, closed-world), yet the description adds real context beyond them: the performance cost of omitting pageId, the return shape for variants vs sets, and a platform-support caveat ('Editors: Design; unverified: FigJam, Slides'). These are genuine behavioral disclosures.

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?

A single dense paragraph front-loaded with what is returned, then scoping behavior, then sibling routing, then platform support. Every clause carries information; nothing is wasted.

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?

With no output schema, the description reasonably covers the returned fields (page, key, description, variant/set attributes) and the two parameters' consequences. It is complete enough to call correctly; only minor error/edge-case behavior is absent, which is acceptable for a read-only lister.

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 baseline is 3, but the description adds meaning beyond the schema's terse 'Omit for the whole document' by spelling out the consequence of omitting pageId (all pages loaded, slow on large files). It does not mention the `session` parameter in prose, keeping it just above baseline.

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+resource ('Components and component sets defined in this file') and immediately scopes it as local (not library). It explicitly distinguishes itself from the sibling figma_get_component by noting that tool 'reads one component's full property definitions,' so an agent can tell the two apart without opening schemas.

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?

Names the alternative (figma_get_component) and its distinguishing purpose, and explains the pageId scoping tradeoff (omit to load every page, which 'takes a moment on a large file'). It stops short of an explicit 'use this when / not when' rule, but the routing signal is clear.

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