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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds genuinely new operational context: statelessness, a 32 KB payload cap, 60 RPM rate limit, demo-mode or L402 payment at 10 sats, and HTTP 400 on invalid input. Those are exactly the facts an agent needs before calling an edge endpoint.

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?

Purpose and the sibling alternative are front-loaded, and every clause carries information. The final sentence is densely parenthetical (limits, auth, defaults, error code all crammed together), which slightly hurts scannability.

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 an output schema present, return values need no explanation; the description instead covers the constraints that matter — size cap, rate limit, auth/payment paths, failure mode, and the sibling escape hatch. Nothing needed for a correct call is missing.

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 the baseline is 3; the description earns above that by disclosing the default value of 'readability_profile' ('article_body_strict'), which the schema does not state. It does not explain include_byline's default, so it stops short of 5.

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 opening sentence gives a specific verb (extracts) and names the exact resources returned: article body, bylines, timestamps, reading duration. It also distinguishes itself from the sibling extract_clean_markdown, so an agent can route correctly without opening either schema.

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 states the use case ('stripping navigation bars, advertisement containers, and cookie banners to isolate core editorial content') and names the explicit alternative with its selection condition ('for converting full HTML to markdown, use extract_clean_markdown instead'). Both when-to-use and when-not-to-use are present.

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