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

Beyond the annotations, the description reveals persistence behavior (30-day link, name rendered only in this response), cost/watermark, and an explicit non-behavior ('Does not post to social networks'). This is substantial context that the structured annotations do not carry, and there is no contradiction.

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?

Four short sentences front-load the core purpose and then add only consequential caveats; every sentence carries information. There is no filler or repetition of the title.

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 an 8-parameter tool with no output schema, the description conveys output format, name privacy, link lifetime, watermark, and what it does not do. It is not fully complete because it omits usage-selection guidance relative to sibling tools and leaves some parameter semantics to schema/enums.

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?

The schema already documents name, locale, background, and previousCodes, so the description only adds a general sense that background is occasion-matched and that decorations are optional. It does not explain style/format or decoration values, leaving 50% schema coverage only partially compensated.

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?

The description opens with a specific action and resource: 'Create a downloadable PNG greeting' with occasion-matched background, curated phrases and optional decorations. It is clear what the tool produces, but it never names or contrasts the sibling tools generate_greeting or list_greeting_options, so differentiation must be inferred.

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?

No when-to-use or when-not-to-use guidance is given, and neither sibling tool is referenced as an alternative. The behavioral caveats (link expiry, watermark, no social posting) are useful but do not help an agent decide between this tool and generate_greeting or list_greeting_options.

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