Browser MCP Server

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

With no annotations provided, the description carries full burden but offers limited behavioral insight. It states the blocking action but doesn't disclose critical traits like whether this is a persistent setting, requires specific browser states, affects performance, or has side effects on other tools. The reference to 'browser_docs' hints at more info but doesn't compensate for the lack of direct disclosure.

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 extremely concise (one sentence) and front-loaded with the core action, avoiding unnecessary words. However, the brevity comes at the cost of completeness, as it relies on an external reference ('browser_docs') without integrating key details.

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 complexity (blocking network requests) and lack of annotations or output schema, the description is incomplete. It doesn't explain what 'block' entails (e.g., immediate effect, error handling), return values, or integration with sibling tools like 'browser_net_start_monitoring', leaving significant gaps for agent understanding.

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 100%, with the 'patterns' parameter well-documented in the schema (including examples like '*.jpg'). The description adds no additional parameter semantics beyond what the schema provides, so it meets the baseline score of 3 without adding value.

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 with a specific verb ('Block') and resource ('requests matching URL patterns'), making it immediately understandable. However, it doesn't explicitly differentiate from sibling tools like 'browser_net_start_monitoring' or 'browser_net_get_requests', which reduces clarity about its unique role in the browser_net family.

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 minimal guidance, only referencing 'browser_docs' for details on URL patterns without specifying when to use this tool versus alternatives. There's no mention of prerequisites, context (e.g., after starting monitoring), or exclusions, leaving the agent to infer usage from sibling tool names alone.

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