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

Annotations already cover safety (readOnlyHint=true, openWorldHint=true). The description adds genuinely new behavior: billing at $0.02 USDC, that failed or empty summaries are not charged, and that it is excluded from the free trial. These cost/failure semantics are not in the annotations and are useful for an agent deciding whether to call.

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?

Two dense sentences, front-loaded with purpose and invocation before pricing. Slightly overpacked but every clause (input modes, options, billing) carries information.

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 not be spelled out, though the description still notes the summary and source details are returned. Combined with the billing disclosure, an agent has enough to call correctly; only explicit sibling routing is absent.

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 both the fields and their enums/defaults are already documented. The description restates text limit (40,000 chars), length values, and format values without adding syntax or constraints beyond the schema, so the baseline 3 applies.

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+resource ('Summarise text or any public web page with AI') with clear scope, distinguishing it from siblings like extract, chat, and page-changes-summary that handle raw content differently.

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?

Explains how to invoke (POST JSON with either 'text' or 'url') and the mutual exclusivity of the two inputs, plus the paid-only caveat. It does not explicitly contrast with sibling tools like extract or docs-answer, keeping it at 4 rather than 5.

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