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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds value beyond these by detailing what it returns (JSON-LD types, headings, etc.) and flagging common link-preview issues (missing og:image, non-absolute URLs). It also discloses pricing. This goes beyond annotations and provides useful behavioral context, though it doesn't cover every edge case like redirect handling.

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 informative but slightly long. It front-loads the core purpose and lists many data points, then gives use cases and pricing. Every sentence earns its place, and the structure is logical. It could be trimmed slightly, but it remains efficient.

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?

With no output schema, the description carries the full burden of explaining return values. It lists what is extracted (title, description, OpenGraph, feeds, JSON-LD, headings) and flags common problems. It also includes pricing and free quota. For a single-parameter tool, this is complete and covers all needed information for an agent to call it correctly.

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?

There is only one parameter, url, and schema description coverage is 0%. The description implies the URL is a page but does not explicitly state format requirements (e.g., http/https, valid URL). Since the parameter name is self-explanatory and the tool context makes it obvious, it adds minimal extra meaning beyond what the schema provides. A more explicit note on URL format would have improved it.

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 with a specific verb ('Everything a page says about itself') and enumerates the exact data it extracts (title, description, OpenGraph, etc.). It distinguishes itself from siblings like web_read by focusing on metadata and link-preview problems, leaving no ambiguity about what it does.

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?

It provides explicit use cases: 'Use to build link previews, check SEO/social cards, find a site's feeds or structured data.' However, it does not explicitly state when not to use it or mention alternatives like web_read for full content, leaving some room for an agent to mis-select. The use cases are clear enough, but exclusionary guidance is missing.

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