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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 does an excellent job describing key behaviors: window shadows/frames are excluded, output can be via file path or Base64 data, AI analysis occurs when a question is provided using auto-selected providers, and temporary files are deleted after analysis. The only minor gap is lack of explicit mention about permissions needed for screen capture or potential rate limits.

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 appropriately sized and front-loaded with the core purpose. It efficiently covers capture targets, output formats, and analysis capability in a few sentences. The version information at the end ('PeepIt MCP 1.0.0-beta.1...') could be considered extraneous but doesn't significantly detract from the overall conciseness.

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?

For a 5-parameter tool with no annotations and no output schema, the description provides substantial context about behavior, use cases, and parameter interactions. It covers the dual functionality (capture + optional analysis) well. The main gap is the lack of information about return values or response structure, which would be important since there's no output schema. However, the description compensates well for the missing annotations.

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%, so the schema already documents all 5 parameters thoroughly. The description mentions some parameters (app_target, format, question) but doesn't add significant semantic value beyond what's in the schema. It provides context about how parameters interact (e.g., path behavior with format='data'), but the schema already covers most of this. Baseline 3 is appropriate when schema does the heavy lifting.

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: 'Captures macOS screen content and optionally analyzes it.' It specifies the verb ('captures'), resource ('macOS screen content'), and optional analysis capability. It distinguishes from sibling tools 'analyze' and 'list' by focusing on capture functionality with optional analysis, rather than pure analysis or listing operations.

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 clear context about when to use this tool: for screen capture with optional AI analysis. It mentions specific use cases like targeting entire screens, app windows, or all windows of an app. However, it doesn't explicitly state when NOT to use this tool or when to prefer sibling tools like 'analyze' (which might be for analyzing existing images rather than capturing new ones).

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