screenshot

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It details the return format (MCP image content block), client compatibility, PNG header dimension extraction, dependency on a fork binary with specific commands, and the structured error behavior for older binaries. This is comprehensive transparency.

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 composed of several concise sentences, each adding distinct technical value: return type, client support, PNG header details, rendering backend, binary prerequisites, and error handling. There is no fluff or repetition.

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?

The description covers return format, compatibility, prerequisites, and error behavior, which is strong for a simple tool. However, it omits an explanation of the session_id parameter and does not explicitly state that the operation is non-destructive (though the context implies it). These are minor gaps.

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 has one required parameter (session_id) with no description, and schema coverage is 0%. The description never mentions session_id, how to obtain it, or its role in identifying the target machine, so it does not compensate for the schema's lack of parameter documentation.

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 opens with a specific verb+resource: 'Capture the current rendered BBC screen as a PNG.' This clearly states what the tool does and inherently distinguishes it from sibling tools like read_memory or read_mode7_text, which extract text or data rather than visual images.

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 implies usage when a visual snapshot is needed and notes that it works in any BBC display mode, but it does not explicitly state when to use this tool versus alternatives (e.g., read_mode7_text for text-based screen inspection) or provide exclusions. The context is clear but not explicitly comparative.

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