read_screenshot

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

Annotations are absent, so description must fully disclose behavior. It only states the operation and return format, missing details on side effects, error handling, file existence checks, or permissions.

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?

Description is brief and structured with Args and Returns, making key info easy to find. However, the misleading required tag on caller_agent_id adds a minor clarity issue.

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?

Covers main purpose, arguments, and return fields. Lacks details on error responses, prerequisites (e.g., file must exist), and output schema specifics. Adequate but not thorough.

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?

Parameter descriptions are minimal (e.g., 'filename: ファイル名') and misleadingly mark 'caller_agent_id' as required while schema allows null. Schema description coverage is 0%, and description fails to compensate with detailed semantics.

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?

Description clearly states the tool reads a specified screenshot and outputs Base64 data. Verb 'read' and resource 'screenshot' are unambiguous, and the tool is distinguished from siblings like 'list_screenshots' and 'read_latest_screenshot'.

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?

No guidance on when to use this tool vs alternatives (e.g., read_latest_screenshot). Does not specify context or exclude conditions.

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