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

Annotations already declare readOnly=false, idempotent=false, destructive=false, openWorld=false, so the mutation profile is known. The description adds substantive context beyond them: the schema v1 validation requirement, the returned design id and editorUrl, and a hard quota (Free accounts save 3 designs total, 1 sheet each, deletions do not restore a save) — a rate/quota disclosure that belongs in prose. It does not explain what happens on validation failure or name collisions, leaving some behavioral gaps for a create operation.

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?

Five short sentences, front-loaded with the action and the payoff (editorUrl) before the quota caveat. Nothing is redundant with the title, and the quota sentence, though the densest, carries information an agent cannot get elsewhere.

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?

There is no output schema, so the description correctly discloses return values (design id plus editorUrl and its meaning, flagged as created by this key). For a nested-object create with hard account limits and no output schema, the description covers validation, return shape, downstream handoff, and quota — everything needed to call it correctly.

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 both parameters are already documented in the input schema and the baseline is 3. The description only adds the constraint that "design" must validate against schema v1, which largely restates the schema's own "(schema v1)" note and gives no added detail about the nested document structure or the name 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?

Opens with a specific verb and resource ("Save a design to the cloud") and states the purpose from the human's side ("so a person can open it in the editor"). It also implicitly separates itself from update_design (new design) and explicitly from open_in_editor and create_share_link, so an agent can distinguish it among 20 siblings.

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?

Gives an explicit workflow: "This is how agent work reaches a human: create it, then hand back editorUrl ... or create_share_link for someone without an account." It names the alternative tool and the condition that selects it (recipient has no account), which is exactly the when-to-use vs. alternative guidance needed.

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