figma_read_canvas

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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, and the description still adds real context: it reads live desktop state rather than cloud state, output format matches get_file/get_node, and token cost is bounded. It does not mention failure behavior when no document is open or how target resolution errors surface, which keeps it from a 5.

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, front-loaded with the distinguishing fact (LIVE document) before the comparison to siblings. No filler.

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?

Six optional parameters with full schema coverage and no output schema, and the description covers the live-vs-cloud distinction, format parity and token budgeting. Minor gaps remain around multi-document targeting and no-document-open behavior, but nothing critical for correct invocation 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 depth, format, target, node_ids, budget_tokens and include_hidden are all already documented. The description reinforces that the output format semantics are identical to get_file/get_node, which helps interpret the format enum, but adds no new per-parameter detail beyond the schema 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 (read) and a precisely scoped resource (the LIVE, currently-open Figma document) with the output shape (Pseudo-JSX/Tree/JSON). It also distinguishes itself from the cloud-API siblings get_file/get_node and from figma_execute_code, so an agent can pick it 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?

Explicitly says to prefer this over hand-writing a tree walk in figma_execute_code and gives the reason (cheaper, format parity). It does not spell out the complementary case (use get_file/get_node when the document is not open locally) or point to figma_list_targets for multi-document targeting in the prose, so the routing guidance is clear but not exhaustive.

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