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

Annotations declare readOnlyHint=true and destructiveHint=false, lowering the bar, and the description still adds real behavior: author.isIntegration flags already-sent replies, a later reply may cancel a remark, and the Figma API cannot mark threads resolved. The last point is a genuinely useful capability limitation. It does not describe pagination or response shape, so it is good but not exceptional.

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?

Three dense sentences, front-loaded with purpose then source semantics then behavioral caveats. No filler. The middle clauses are slightly compressed but every sentence carries information.

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 list tool with no output schema, the description covers purpose, source options, integration markers, and a key API limitation. It omits return ordering/pagination and does not explicitly route to design_comment_reply, so it is complete-ish but not fully self-sufficient.

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 all three parameters (url, status, designID) are already documented in the schema. The description adds scoping semantics (frame/page returns threads inside it, file returns all; designs key or design:<uuid> form), which is a modest value-add over the schema. Baseline 3 is appropriate when the schema does the heavy lifting.

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: 'Returns Figma design comments', enumerated as threads with author, date, text, replies, pinned node. Clear what it does. It does not explicitly name or contrast with its closest sibling design_comment_reply or design_import, so it stops short of full sibling differentiation.

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?

Usage is implied by the source semantics (url vs designID) but the description never says when to use this versus design_comment_reply or design_import. An agent must infer that this is the read tool and design_comment_reply the write tool.

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