clear_display

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

Annotations declare mutation (readOnlyHint=false), idempotency, and non-destructiveness, but the description adds the critical context the annotations hide: existing content is discarded and the pending expiry timer is cancelled. That side-effect disclosure is exactly what an agent needs before overwriting a user's screen; only the return/result state is left unstated.

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?

A single sentence with no filler, and the primary action is front-loaded ahead of the secondary timer-cancellation detail.

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 parameterless, annotation-covered tool this covers action and side effect adequately; the only gap is that no output schema exists and the description doesn't say what is returned or what state the display reports afterward.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies.

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 concrete verb+resource pair ('Replace screen content with a blank dark canvas') plus the secondary side effect ('cancel its expiry timer'), which clearly distinguishes it from the display_message/display_image siblings. It stops short of naming those siblings explicitly, so differentiation relies on inference.

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?

Usage is only implied – an agent can infer 'use this to wipe the screen' from the word 'Replace', but there is no explicit when-to-use, when-not, or reference to preview_display/display_image as alternatives.

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