Preview a link

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds the useful framing that it never fetches page content, but it omits the one-hour caching behavior and the existence of the fresh/render/verify_image bypasses, leaving those solely to the schema. Adds some value, but not rich behavioral context.

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 no waste: the first front-loads verb plus resource plus return surface, the second earns its place by supplying the usage context. Nothing is padded or repeated.

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?

There is no output schema, and the description compensates by enumerating the returned fields (title, description, image, favicon, site name, author, date, language, feeds), so the agent knows what to expect. Combined with annotations covering the read-only/open-world profile, nothing needed to invoke it correctly is missing.

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 every parameter including fresh, render and verify_image is already documented in the schema. The description adds nothing about parameter syntax or defaults, which is the correct baseline when the schema does the heavy lifting.

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 ('Reads the metadata of a public URL') and enumerates exactly which metadata fields come back. The closing clause ('without reading the page') implicitly contrasts it with the sibling read_webpage, but never names that alternative, so the differentiation is inferential rather than explicit.

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?

'A quick way to learn what a link points to without reading the page' implies the selection criterion versus read_webpage, but no tool is named and no exclusions or prerequisites are stated. Usage is implied rather than spelled out.

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