Generate a social card image

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

Annotations already declare a non-read-only, open-world, non-idempotent write, and the description is consistent with that by describing creation. It adds genuinely new behavioral context the annotations cannot convey: the returned link is valid for only seven days, and the image itself is returned alongside it.

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, zero waste, with the core identity ('Open Graph image') front-loaded before the inputs and the return contract. Every clause 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?

With no output schema, the description carries the return-value burden and does so adequately by stating both the link (with its seven-day validity) and the image. It stops short of clarifying the image's form (binary vs URL) or any size/rate limits, minor gaps for an otherwise complete definition.

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% with enums for font, size, theme, format and template, so the schema already documents every parameter in detail. The description names title, subtitle, site and logo but adds no syntax or constraint beyond what the schema provides, 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 and resource ('Creates an Open Graph image') and immediately glosses the concept as 'the card shown when a link is shared', which no sibling tool produces. An agent can tell it apart from capture_screenshot, render_html or generate_qr_code without opening the schema.

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?

The description contextualises when the output is useful ('shown when a link is shared'), implying the use case, but gives no explicit when-to-use or when-not-to-use guidance and never names an alternative. With no exclusions, an agent must infer this over render_html or preview_link itself.

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