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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds valuable context beyond these: it states a ~10 second latency, that HTTPS is required and PDFs are rejected (hard errors), and details the response structure (success, data.markdown, large metadata with og/twitter tags, statusCode, sourceURL, language). 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?

The description is front-loaded with the core action, then requirements, output shape, timing, constraints, and usage guidance. It is a little long but every sentence adds value, and the structure is logical. No fluff or repetition that doesn't earn 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?

Given the tool has only 3 parameters and an output schema exists, the description fully covers what an agent needs to call it correctly: required fields, constraints, expected response, latency, and when to use alternatives. Nothing essential 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?

The input schema already covers all three parameters with descriptions and examples (100% coverage). The description adds extra constraints: url must be HTTPS and not a PDF, proxy must be explicitly set to 'basic' on the metered profile, and formats must be exactly ['markdown'] when present. This enriches the schema meaning, though the schema already carried most of the burden.

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 opens with a specific verb and resource: 'Fetch one URL and get its main content back as markdown.' It immediately differentiates from siblings by naming the batch scraper, the Tavily extractor, and the map tool, so an agent can tell exactly when this tool is the right one.

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?

Explicit guidance is provided: 'Use it when you have the URL and want the text.' It then contrasts with alternatives: for multiple URLs use post_firecrawl_batch_scrape or post_tavily_extract, and to discover URLs first use post_firecrawl_map. This is textbook usage guidance.

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