extract_metadata

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

With no annotations provided, the description carries full burden and does an excellent job disclosing behavioral traits: explicitly states 'Read-only — makes no changes to any external system', discloses authentication requirement ('Requires HAUNT_API_KEY environment variable'), and provides rate limit information ('Free tier: 100 requests/month'). It also mentions error conditions for rate limits and invalid API keys.

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?

The description is perfectly structured and concise: first sentence states purpose, second describes output format, third lists use cases, fourth provides sibling differentiation, and final sentences cover behavioral constraints. Every sentence earns its place with zero waste.

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?

For a single-parameter tool with no annotations and no output schema, the description provides excellent context: clear purpose, usage guidelines, behavioral transparency, and output format description. The only minor gap is that without an output schema, the description could provide more detail about the structured JSON format returned.

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 the schema already documents the single 'url' parameter adequately. The description doesn't add meaningful parameter semantics beyond what the schema provides (e.g., no format examples, no constraints on URL types). Baseline 3 is appropriate when 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?

The description clearly states the specific action ('Pull metadata') and resource ('from any URL'), listing exact metadata types extracted (title, description, Open Graph tags, Twitter cards, canonical URL). It distinguishes from siblings by explicitly mentioning extract_url and extract_article as alternatives for different content types.

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?

Explicit guidance is provided: use this tool for metadata extraction, use extract_url for page body content, and use extract_article for full articles. Clear when-to-use and when-not-to-use scenarios are defined with named alternatives.

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