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

Annotations only declare readOnlyHint and openWorldHint, so the description carries the rest and does it well: per-mode latency expectations are embedded, and the cost model is disclosed precisely ('fast 1 credit, standard 2 credits, thorough 5 credits, charged only when a call succeeds'). The charge-only-on-success detail materially affects how aggressively an agent retries or upgrades modes.

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?

Front-loads purpose and return shape, then usage, then mode escalation, then sibling alternatives, then cost. Every sentence carries distinct information and nothing is repeated from the annotations or schema.

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 compensates by stating what is returned (content in the chosen format plus title, description and links), and it covers the operational concerns a 5-parameter open-world scraping tool raises: cost, latency per mode, and fallback routing to documents/screenshot.

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 schema already documents each parameter's enum values and defaults; the baseline is 3. The description adds a decision rule not present in the schema ('start with fast', standard for JS-heavy pages, thorough only for scraper-blocking sites), which is actionable parameter guidance beyond the raw enum text.

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?

States a specific verb and resource ('Extract content from any URL as Markdown or HTML') and immediately distinguishes itself from siblings by naming documents and screenshot as the alternatives for those use cases. An agent can tell exactly what this tool produces without opening the 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?

Gives an explicit trigger ('Use when you have a URL and need what the page says'), a mode-selection rule ('Start with fast; use standard for pages that need JavaScript and thorough only for sites that block scrapers'), and named alternatives for adjacent needs ('To pull specific fields into JSON use documents; to see the page as an image use screenshot'). This is when/when-not/alternatives in full.

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