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

No annotations exist, so the description carries the full behavioral burden. It states the input/output contract but stays silent on whether generation involves a network call, whether the returned URL is persistent or temporary, rate limits, and failure behavior on invalid width/height values. For a tool that generates a remote resource, this is a meaningful gap.

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 with the core action front-loaded and no filler. The 'Og Image:' label slightly duplicates the tool name, and 'returns an OG image link' mildly restates the earlier 'Generate an Open Graph image URL,' but overall the structure is tight and scannable.

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?

With no annotations and no output schema, the description is the sole source of operational context, yet it stops at the minimal input→output contract. Missing details an agent needs for correct invocation include width/height units, default behavior when optional params are omitted, URL persistence/expiry, and whether title is truly required despite the schema declaring zero required parameters.

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%, establishing the baseline of 3. The description adds one genuinely useful semantic: width and height are 'optional' and title is the primary input, which partially reconciles the schema's zero required parameters. But it does not add units (pixels?), defaults when omitted, or value constraints, leaving the generic 'Width to process' schema text as the only guidance.

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 uses a specific verb and resource: 'Generate an Open Graph image URL from a title,' and it discloses the output form ('returns an OG image link'). The OG-from-title focus implicitly separates it from image-adjacent siblings like x402-placeholder-image, x402-avatar-generate, and x402-gradient-generate, though it never names them.

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?

'Provide title and optional width/height' gives direct invocation guidance, and the return-value statement sets output expectations, so usage is implied but functional. However, there is no when-to-use/when-not-to-use guidance or reference to alternatives, which matters in a catalog of thousands of x402-* tools.

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