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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is covered. The description adds only that images are optional and that output is a PNG plus a Next.js file; it does not explain rendering failures, size/weight limits, or what happens with fields not used by the chosen template.

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?

Two sentences, front-loaded with the action and outputs, then the required inputs. No filler or restated boilerplate.

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?

An output schema exists, so return values need not be described. However, for a 33-parameter, 18-template tool with zero required parameters, the description gives no sense of which fields belong to which template, forcing the agent to guess or re-query list_og_templates.

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 only 30% across 33 parameters, but the description does group them conceptually (template-specific fields, colors, size, optional base64 images) and notes that only 'the fields that template uses' matter, which is real semantic guidance. It stops short of enumerating the many text fields (quote, steps, versions, before/after values) that are undocumented in the schema.

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 (render Open Graph templates) plus both output artifacts (PNG and opengraph-image.tsx). It also ties itself to the sibling list_og_templates for template ids, so an agent can distinguish it from build_json_ld and list_og_templates at a glance.

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?

It establishes a clear workflow precondition: get the template id from list_og_templates, then pass the fields that template uses. There is no explicit when-not-to-use or exclusion, but the routing to the sibling is concrete and useful.

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