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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so safety and retry semantics are covered. The description adds real behavioral context beyond them: a library component is imported first and then placed, and editor support varies. It stops short of describing what the call returns or where the instance lands by default, but the added side-effect disclosure is meaningful.

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?

Front-loaded with the core action and then layered with routing, the id-source rule, the exclusivity constraint, and platform support. Dense but every clause carries information; the only mild cost is that the exclusivity rule is buried mid-paragraph rather than stated up front.

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 10-parameter mutation tool with no output schema and 80% schema coverage, the description covers the id-source workflow, the exclusivity constraint, the import side effect, and the sibling alternative. It does not say what the call returns (e.g. the new node id) or the default parent behavior, which are the remaining minor gaps given annotations already carry idempotency and safety.

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 80%, so the baseline is 3, but the description adds a constraint the schema does not encode: 'Give exactly one of componentId, componentKey, componentSetKey' (no oneOf in the schema). It also clarifies variant defaulting, which exceeds the schema's own description. That mutual-exclusivity rule is exactly the kind of semantics an agent cannot infer from structured fields.

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 (place) and resource (instance of a component/component set variant), enumerating the three modes of placement. It explicitly distinguishes itself from siblings figma_swap_component and figma_import_library_assets, so an agent can route correctly without opening a 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 routing: local ids come from figma_get_local_components, library components are imported then placed, and the alternative for changing an existing instance is figma_swap_component. It also names the required version support (Design; unverified FigJam/Slides), which is genuine when-to-use guidance.

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