Url Social Cards

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

Annotations already declare readOnlyHint and idempotentHint, so the bar is lower. The description adds valuable context: no JavaScript execution, no access control bypass, bounded extraction, and caching behavior. No contradictions with annotations.

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 sentences, each carrying distinct and essential information: purpose, constraints, and parameter behavior. No extraneous details. Front-loaded with purpose.

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?

The tool is simple with 2 parameters, schema covers all, annotations present, output schema exists. The description covers purpose, constraints, caching, and parameter usage adequately. No gaps for efficient agent invocation.

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%, so baseline is 3. The description adds value by explaining the caching logic ('fresh=false to allow cache reuse; fresh=true only when a new upstream fetch is required') and reinforcing that url must be a public HTTP(S) URL, which is not fully detailed in the schema description alone.

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 clearly states 'Extract bounded Open Graph and Twitter Card fields,' using a specific verb and resource. Among siblings like url_metadata and url_jsonld, this tool is distinct for OG and Twitter cards, avoiding ambiguity.

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 explicitly says 'Use only for public HTTP(S) resources' and clarifies that it does not execute JavaScript or bypass access controls. It also explains when to use fresh=true vs fresh=false. However, it does not explicitly name alternative tools for when to not use this one.

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