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

With no annotations, the description carries the full burden and largely does so: robots.txt compliance, no JS rendering, stripping of nav/ads/scripts, 'not charged if the page cannot be read', and rate/pricing limits (5 free calls/day, 0.005 USDC per call via prepaid key). These are non-obvious behavioral traits an agent must know before calling.

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 output shape are front-loaded, followed by constraints and then billing. Dense but every sentence carries information; the billing sentence is slightly packed but still earns its place.

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?

No output schema and no annotations, yet the description covers what the return payload contains, what is stripped, rendering limitations, compliance behavior, and cost model. Nothing an agent needs to call it correctly 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 schema already documents url, links, max_chars and key. The description adds only pricing/billing context for key ('pass key to use a prepaid balance') and does not explain links or max_chars behavior. Baseline 3 is appropriate when the schema does the heavy lifting.

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 ('Fetch a public web page') and enumerates exactly what is returned: title, description, language, publish date, and article text with headings, lists, tables, code blocks and links. This is far more specific than any sibling (balance, check_domain, create_key), so an agent can route to it unambiguously.

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 clear intended context ('Built for LLM agents that need to read a URL') and meaningful exclusions: static HTML only, no JavaScript rendering, and robots.txt is respected. It does not explicitly compare against a sibling alternative, but the siblings are largely unrelated, so the boundary is inferable.

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