Screen MCP

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 effectively describes the tool's behavior: it returns metadata and an ASCII preview, and it's used after capture initiation to discover chunk counts. However, it doesn't mention potential errors (e.g., invalid capture_id), rate limits, or authentication needs, leaving some behavioral aspects uncovered.

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 highly concise and well-structured with two sentences. The first sentence states the purpose, and the second provides usage guidelines. Every word earns its place, with no redundancy or fluff, making it easy to parse and understand quickly.

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 (1 parameter, no annotations, but with an output schema), the description is complete enough. It explains the purpose, usage sequence, and key outputs (metadata, ASCII preview, total_chunks discovery). Since an output schema exists, the description doesn't need to detail return values, and it adequately covers the tool's role in the workflow with sibling tools.

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 input schema has 0% description coverage for its single parameter 'capture_id'. The description compensates by implicitly explaining the parameter's role: it refers to 'after `start_screenshot_capture`', indicating capture_id likely comes from that previous step. This adds meaningful context beyond the bare schema, though it doesn't specify format or constraints explicitly.

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: 'Return screenshot session metadata and an ASCII preview.' It specifies both the resource (screenshot session) and the output (metadata + preview), distinguishing it from siblings like 'get_screenshot_chunk' or 'capture_screenshot' by focusing on manifest retrieval rather than chunk data or capture initiation.

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 usage guidance: 'Use this as step 2 after `start_screenshot_capture` to discover `total_chunks` and preview content.' It specifies the exact sequence (after start_screenshot_capture) and purpose (discover total_chunks and preview), clearly differentiating when to use this tool versus alternatives like 'get_screenshot_chunk' for actual data retrieval.

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