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

Annotations declare readOnlyHint and openWorldHint, and the description stays consistent while adding substantial beyond-schema behavior: hidden elements, HTML comments, invisible characters and injected instructions are stripped, links are rated, and known-malicious pages are never fetched. The one gap is what the caller actually receives when a page is blocked (error vs. empty result).

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?

One front-loaded sentence with no filler; every clause contributes a distinct behavior (check, fetch, sanitize, rate links, block malicious). The sentence is long but each segment 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?

There is no output schema, so the description carries the return-value burden and does so: readable text plus per-link safety ratings. Remaining gaps are secondary — exact response shape and the failure mode for blocked pages — which matter less for a read-only fetch tool.

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?

With schema coverage at 50%, the description only implies that 'url' is the page to fetch and says nothing about the optional api_key or the 25/250 daily-limit semantics (those live in the schema text). The url parameter's meaning is self-evident from the prose, but the description adds no real meaning beyond the schema.

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?

Names a concrete verb+resource ('Safe browser... fetches it, returns readable text') and describes the composite pipeline (check, fetch, sanitize, rate links) that distinguishes it from single-purpose siblings like check_url or check_site. It stops short of explicitly naming a sibling alternative, so differentiation is inferred rather than stated.

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?

Usage is implied by 'in one call' and 'so you know which are safe to follow next,' which sketches a workflow: use this instead of separate check-then-fetch calls. However, no explicit when-to-use/when-not conditions or named alternatives (report_page, check_site) are given.

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