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

Annotations declare destructiveHint=true and idempotentHint=true but say nothing about reversibility or auth. The description adds that screens revert to their normal schedule on expiry, that it returns a castId routable to end_cast, and that it requires `screen.cast`. That is substantive context beyond the structured fields, and it does not contradict the destructive flag.

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?

Front-loaded with the core behavior, then scope, then the canonical example, then alternatives, then the return/permission notes. Every sentence carries distinct information with no filler.

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 purpose, scope options, reversibility, the stop-early path via end_cast, the permission requirement, and sibling routing. With an output schema present, it does not need to detail return shape, and it still surfaces the castId handoff that matters operationally.

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%, so the baseline is 3. The description adds real value by explaining the scope axis ('everything (all), an org node subtree, or explicit screenIds') and reinforcing that contentId must reference EXISTING content, mapping the two enum parameters to intent rather than just restating them.

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?

States a specific verb+resource+behavior: 'Show EXISTING content on screens as a TIMED takeover (a cast)'. It explicitly distinguishes itself from siblings assign_content, quick_post, and trigger_emergency_template, so an agent can route correctly without opening schemas.

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?

Gives a concrete usage scenario ('put the lunch menu on the lobby screens until 2pm') and explicit alternatives with selection conditions: assign_content for a lasting change, quick_post to write new content, trigger_emergency_template for emergencies. Nothing is left to inference.

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