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

Annotations already declare the safety profile (readOnly, idempotent, non-destructive, closed-world). The description adds meaningful context beyond them by clarifying the return format ('Returns SVG markup, not a photorealistic likeness'), which sets correct output expectations. It doesn't discuss the deterministic-seed behavior, but that is documented in the schema.

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 tight sentences with no waste; purpose comes first, then usage, then the output-format caveat. Every sentence earns its place.

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?

No output schema exists, but the description compensates by stating the tool returns SVG markup. With full parameter coverage and complete annotations, an agent has everything needed. Only minor gaps (e.g., seed determinism) remain, and those are covered by the schema.

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% with a documented enum and per-field descriptions, so the schema carries parameter meaning fully. The description adds no syntax or format detail beyond it, so the baseline 3 applies.

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 ('Create an SVG placeholder profile icon') and immediately scopes the output type. Distinguishable from sibling generators like generate-color or generate-hash by naming the artifact produced.

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?

Provides clear context ('Use for synthetic avatars in demos and UI prototypes'), which tells the agent when the tool is appropriate. It does not name alternatives or explicit exclusions, but the sibling set is a homogeneous generator family and none overlaps here.

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