URL metadata

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

No annotations are provided, so the description carries the full behavioral disclosure burden. It discloses a cost behavior ('Costs $0.01 per call, paid in USDC on Base') which is valuable. However, it does not mention authentication requirements, rate limits, failure modes, or explicitly confirm that it only reads data and does not modify anything. The cost and normalization hint are useful but incomplete.

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 three sentences with every sentence earning its place: the first lists the output fields, the second gives use cases, and the third states cost. It is front-loaded with the core purpose and contains no filler or redundancy.

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 simple one-parameter tool with no output schema, the description is quite complete. It lists the exact fields the agent can expect (title, description, canonical URL, OpenGraph, etc.), covers use cases, and discloses cost. It does not describe error behavior or output serialization, but given the low complexity, these are minor gaps that do not prevent correct 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% – the only parameter 'url' is described as 'Absolute http(s) URL of the page to process.' The description adds no extra parameter-level guidance beyond the schema; it mentions web page metadata but does not elaborate on URL edge cases or formats. The baseline of 3 applies because the schema already documents the parameter fully.

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 states exactly what the tool does: 'Normalised metadata for a web page: title, description, canonical URL, OpenGraph and Twitter card fields, icons, language, robots directives, author and dates.' It enumerates the specific resources it retrieves, which clearly distinguishes it from siblings like farm_links (links only) and farm_jsonld (JSON-LD only). The purpose is unambiguous and immediately actionable.

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 provides explicit use cases: 'Use this for link previews, deduplication or classifying a URL.' This gives clear context for when to invoke the tool. However, it does not name sibling alternatives or state conditions for when NOT to use it, so it stops short of the full 5-level guidance.

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