generate_og_image

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

With no annotations, the description carries the full burden and does disclose meaningful traits: the tool returns both a hosted URL and PNG/SVG bytes, and identical renders are cached and not double-billed, which is real cost/idempotency context. It omits auth requirements, rate limits, or text-length constraints.

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 short sentences, each carrying distinct information: what is produced, what is returned, and how repeat calls are billed. Front-loaded with the core action and dimensions.

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, so the description must cover returns, and it does (hosted image URL plus PNG/SVG bytes). For a simple three-parameter generation tool with no annotations this is nearly complete, with only auth and size-limit behavior left unstated.

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 description coverage is 100%, so the baseline is 3. The description restates title and tag line and hints at format via 'PNG/SVG bytes', but adds no syntax, length, or defaulting detail beyond what the schema already documents.

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 with concrete dimensions: 'Generate a 1200x630 Open Graph (social preview) image from a title and optional tag line.' The only sibling, get_quota, is an unrelated quota utility, so there is no ambiguity to disambiguate.

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 description (social preview cards from a title), but there is no explicit when-to-use statement, no prerequisites, and no alternatives named. Nothing is misleading, but nothing routes the agent either.

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