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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint. The description adds useful context: 'No AI — fast and deterministic,' pricing ($0.002), and payment method (x402). No contradiction with annotations.

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 sentences, concise and front-loaded. The first sentence conveys the core action and method. The second provides alternatives and pricing. Could be slightly more compact but effective.

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?

Given the tool's simplicity, full schema coverage, and presence of annotations and output schema (not shown but indicated), the description is complete: it explains functionality, method, alternatives, pricing, and constraints.

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 description coverage is 100% (both parameters described). The description adds the algorithm name (TextRank) and default value for sentences, but does not significantly extend beyond the schema's parameter descriptions.

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 specifies the tool's purpose: fetch a URL, extract main article, return key sentences via TextRank. It distinguishes from full scraping and AI summarization by explicitly contrasting with POST /api/summarize-text.

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?

The description states when to use: 'for agents that want the gist of a page, not a full scrape.' It also provides an explicit alternative for AI summarization or different input types (PDF/DOCX/own text) via a POST endpoint.

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