Screenshot

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

No annotations are provided, so the description carries the full burden. It mentions the output format (PNG) and visual fidelity, but fails to disclose critical behavioral traits such as whether this requires an active session, permissions needed, file storage location, error conditions, or 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 front-loaded with the core purpose in the first sentence, and the second sentence adds valuable context without redundancy. Both sentences earn their place, making it appropriately sized and efficient.

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 (capturing visual output) and lack of annotations or output schema, the description is incomplete. It omits details on behavioral aspects like error handling, file output specifics, or dependencies on session state, which are crucial for effective use.

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 the single parameter 'sessionId'. The description does not add any meaning beyond what the schema provides, such as explaining what a sessionId is or where to obtain it, but the baseline of 3 is appropriate given high schema coverage.

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 specific action ('Capture') and resource ('terminal as a PNG image'), and distinguishes it from siblings like 'snapshot' by specifying the output format and visual fidelity ('Shows exactly what a user would see - colors, styling, layout').

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 explicit guidance on when to use this tool versus alternatives like 'snapshot' or 'read_region' is provided. The description implies usage for capturing visual terminal state but lacks context on prerequisites, exclusions, or comparisons to sibling tools.

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