Block resource types

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

Beyond annotations, the description discloses session-scoped persistence across navigations, the reset mechanism, and specific side effects on stylesheet-blocking for geometry-dependent operations. This enriches the idempotentHint with concrete behavioral expectations and potential failure modes.

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 three short paragraphs, each serving a distinct purpose: primary function, use-case benefit, and side-effect/scope warning. Every sentence earns its place with no repetition or filler, and the most important information is front-loaded.

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 a single parameter fully described in the schema and an output schema present, the description covers behavior, side effects, scope, and reset, making it fully actionable for an agent. No additional return-value documentation is needed given the output schema.

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 schema already provides 100% coverage, including recommended enum combinations and unblock semantics. The description adds value by explaining why stylesheet blocking breaks layout and reinforcing the trade-off, going slightly beyond the schema without duplicating it.

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 states the tool's function: blocking images, fonts, stylesheets, or media to speed up page loads. It distinguishes itself from sibling tools by specifying the resource types and the performance motivation, making its purpose unambiguous.

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 provides explicit when-to-use guidance (media-heavy pages, metered/proxied connections) and when-not-to-use (when layout-dependent behavior is needed, listing affected tools like click_at and wait_for_selector). It also explains how to reset via calling with no types, giving clear operational boundaries.

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