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

Annotations already declare readOnly/openWorld/idempotent/non-destructive, but the description adds material context beyond them: robots.txt compliance, SSRF guards, partial-failure skipping, same-host enforcement, and exact metering terms (shared 100/day free bucket, 3 credits over x402, no API key). This is precisely the behavioral disclosure an agent needs before spending quota.

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-loaded with purpose, then labeled When/Do-not/Returns/Behavior/Metering segments. Despite being information-dense, every sentence carries a distinct operational fact with no filler or repetition.

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 exists, yet the description spells out the exact return object shape ({ok, url, final_url, count, pages[...], cached, took_ms, _metering}) and notes partial failures are skipped. Combined with metering and safety notes, an agent has everything needed to call and interpret this tool correctly.

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 url, depth, max_chars, and max_pages are already documented. The description reinforces the depth range and page cap but adds no new per-parameter semantics (no guidance on when to choose depth 1 vs 2 or how max_chars affects cost), 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 and resource ('Crawl one site's same-host pages starting from a URL') with scope bounds (depth 1-2, ≤20 pages) and names what it returns. It is immediately distinguishable from web_fetch (single page) and web_map (URL listing) by explicit sibling naming.

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?

Provides an explicit 'When to use' condition (several pages from one site: docs section, news index, product list, and web_map is insufficient) and an explicit 'Do not use' clause routing single pages to web_fetch and full mirrors away. Alternatives and exclusions are both stated, leaving nothing to inference.

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