capture_window_and_post

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

No annotations are provided, so the description carries full burden. It details key behaviors: fallback to fullscreen (with allow_fullscreen parameter explaining error vs silent posting), default window title via environment variable, and that thread_ts is for replying. Minor omission is the exact return value, but echo_image parameter partially addresses output.

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 main description is two concise sentences. Parameter descriptions are detailed but not verbose. Overall well-structured and easy to parse, though slightly longer due to complete parameter documentation.

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 8 parameters, no output schema, and no annotations, the description covers the tool's purpose, use case, and parameter details well. However, it does not explicitly describe the return value when echo_image is false (e.g., whether it returns a review_id or just posts), leaving some ambiguity.

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 coverage is 100%, but the description adds value beyond schema. For example, title parameter explains its dual role as card header and file title, window parameter explains default env var and special values like 'active', and allow_fullscreen explains error behavior. This extra context justifies above baseline 3.

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 'Screenshot the running app window (X11/KDE) and post it to Slack as a review.' It provides a specific verb, resource, and action, and explicitly distinguishes from sibling tool send_to_slack by specifying when to use each.

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 explicitly states when to use this tool ('only when no offscreen render exists') and when to prefer the alternative ('otherwise prefer send_to_slack with a repro-rendered PNG'). This is strong usage guidance.

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