Browser MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the tool controls media elements but doesn't describe what happens if the selector fails, whether actions are synchronous, if there are side effects (e.g., UI changes), or error conditions. The mention of 'see browser_docs' hints at more info elsewhere but doesn't add transparency directly in the description.

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 very concise—a single sentence that states the purpose and references documentation. It's front-loaded with the core functionality. However, the parenthetical reference to browser_docs adds minor clutter without providing immediate value, slightly reducing efficiency.

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's moderate complexity (3 parameters, no output schema, no annotations), the description is minimally adequate. It states what the tool does but lacks details on behavior, error handling, or integration with siblings. The reference to browser_docs suggests more context exists externally, but the description itself is incomplete for standalone use.

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 description coverage is 67% (2 out of 3 parameters have descriptions). The description adds no parameter-specific information beyond what's in the schema—it doesn't explain selector syntax, action details, or value usage. With moderate schema coverage, the baseline is 3, as the schema does most of the work but the description doesn't compensate for the 33% gap (the 'action' parameter lacks a schema description).

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: 'Control a media element (play, pause, seek, mute)' with a specific verb ('control') and resource ('media element'). It distinguishes from siblings like browser_get_media_summary (which reads media info) and browser_start_video_recording (which records media). However, it doesn't explicitly differentiate from all siblings, just implies it's for control rather than reading/recording.

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 no guidance on when to use this tool versus alternatives. It mentions 'see browser_docs' for more information, but this is not explicit usage guidance. There's no mention of prerequisites (e.g., needing a media element present), exclusions, or comparisons to similar tools like browser_get_media_summary for reading media state.

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