Extract page metadata

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

The description adds value beyond annotations by stating the tool avoids fetching the page twice, implying efficiency. It also discloses the breadth of metadata extracted (e.g., JSON-LD, RSS feeds, hreflang). No contradiction with annotations (readOnlyHint, idempotentHint, etc.).

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 well-structured sentences: the first lists all extracted metadata types, the second provides usage guidance. No fluff, every phrase adds value. Front-loaded with key information.

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?

Given the complexity (5 parameters, sibling tools), the description is complete. It covers purpose, usage, output scope, and efficiency benefits. The presence of an output schema means return values need no further explanation.

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 does not add parameter-level details beyond the schema, but the schema descriptions are self-explanatory (url, timeoutMs, booleans). No extra semantic value from description.

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 tool's purpose: extracting structured metadata from a web page without downloading it twice. It lists 12 specific metadata elements (title, meta description, etc.), which distinguishes it from sibling tools fetch_page_markdown and extract_links.

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 advises using this tool 'to classify or summarise a page cheaply before fetching its full text,' providing clear context for when to use it. It does not mention when not to use it or name alternatives, but the guidance is sufficient.

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