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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the mutation profile is covered. The description adds context beyond annotations: the create-then-edit sequential workflow (call this first, then use returned design_id with start-editing-transaction and editing tools), and the requirement to obtain candidate_id from generate-design results. It does not contradict the annotations.

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?

The description is longer than average but every block earns its place given the complex routing requirements. The 'LEGACY-ONLY' warning and brand exception are front-loaded before the core workflow. Slight redundancy exists (the DO NOT CALL constraint is stated twice), and the routing block could be tightened, but the structure is effective and information-dense rather than padded.

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 tool in a 33-sibling ecosystem with no output schema, the description handles the return value itself ('design summary containing a design ID') and the cross-tool sequencing with generate-design and start-editing-transaction. One minor gap: the routing condition references create-design, which is not actually present in this tool list — the conditional is somewhat hypothetical here, though the description does gracefully state it applies 'when create-design is absent from the tool list.'

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. The description adds value beyond the schema by explaining the provenance of both job_id and candidate_id ('returned in the generate-design response') and the ordering requirement linking them to the generate-design pipeline. This ties each parameter to its upstream source, which the schema alone does not convey.

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 and resource — 'Create a new Canva design from a generation job candidate ID' — and clarifies the mechanism: 'converts an AI-generated design candidate into an editable Canva design.' This distinguishes it from generate-design (which produces candidates) and create-design-from-brand-template (brand-templated variants), so an agent can separate it from siblings 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?

Exceptionally explicit routing: it names the preferred alternative (create-design), forbids calling this tool when that alternative is present, and carves out a precise brand exception ('brand kit, brand colours, fonts or logo, brand template'). It also notes that a failed create-design call does not make this tool available. This is textbook when-to-use vs when-not-to-use guidance.

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