emulate_media

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

The description discloses key behavioral traits beyond annotations: the emulation is temporary (until reset or reload), and it details the scope of userAgent override (only page JS, not HTTP header). Annotations indicate idempotentHint=true and destructiveHint=false, which are consistent. No contradictions.

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 concise (two sentences) and front-loaded with the primary purpose. Every sentence adds value: first sentence defines the tool and lists overrides; second sentence clarifies a common confusion (userAgent vs header) and suggests a pairing. No wasted words.

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 complexity (6 parameters, no output schema), the description covers the main functionality, scope (until reset/reload), and relevant sibling tools. It does not explicitly describe the reset parameter's effect or return values, but these are handled by the schema. Overall it provides sufficient context for an agent to understand and invoke the 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 baseline is 3. The description adds context about the overall effect (e.g., 'print mode' overrides matchMedia) and relationships to other tools, but does not provide additional meaning for individual parameters beyond the schema descriptions. It adds moderate value but not significant per-parameter detail.

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 purpose: making the page believe it runs in a different environment, listing specific overrides (prefers-color-scheme, prefers-reduced-motion, print mode, userAgent/platform). It distinguishes from sibling tools like network_rules for user-agent headers and suggests pairing with viewport_resize for device emulation.

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 guidance on when to use alternatives (e.g., network_rules for modifying the User-Agent HTTP header) and suggests pairing with viewport_resize for device emulation. However, it does not explicitly mention when to use the reset parameter or when the tool is not appropriate.

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