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

Beyond the annotations (destructiveHint=true, openWorldHint=true), the description discloses concrete side effects: a remote end may be sent, the device's ActivityKit push budget is consumed, and subsequent set_live_activity_stream calls are suppressed. It also names the recovery path (resume_live_activity_stream), which the annotations cannot convey.

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?

Three sentences ordered as action, cautionary guidance, then state consequence. The scoping and budget warning is front-loaded and no sentence is redundant or padding.

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 destructive, budget-consuming operation with two documented parameters and an output schema, the description covers the important unknowns: what gets destroyed, what it costs, and what state results. Return-value detail is correctly left to the output schema.

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 stream_key and content_state are already documented, including key reuse and budget warnings in the schema itself. The description adds no parameter-level syntax or format detail, so the baseline 3 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 specific verb (pause) and resource (Live Activity stream) and clarifies the composite effect: ending the current activity when needed. It also implicitly distinguishes itself from set_live_activity_stream and resume_live_activity_stream by name, so an agent can separate it from its closest siblings without opening a schema.

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?

Explicit when/when-not guidance: 'use it only for a genuine pause, not as update-rate control,' plus the consequence that future set_live_activity_stream calls are ignored until resume_live_activity_stream is called. This routes the agent to the correct sibling for rate changes and explains the state transition required to undo it.

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