Inject an external observation or state change

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

With no annotations, the description carries the full burden. It discloses the async nature and that the step count is not advanced, which is useful. However, it does not mention the potentially state-mutating state_patch behavior or any side effects beyond delivering the observation, leaving part of the behavioral profile to the schema.

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?

Two sentences with no wasted words: the primary purpose is front-loaded, followed by a high-value behavioral caveat. Every clause earns its place.

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 moderately simple injection tool, the combination of description and schema covers the required parameters, the optional state_patch semantics, and the key behavioral distinction (no step count advance). Missing details like return values and error behavior are not critical for invoking the tool correctly, and no output schema exists to contradict this.

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 all parameters and their meanings. The tool description adds little beyond examples already present in the observation parameter's schema description, so baseline 3 is appropriate.

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 action ('Deliver an asynchronous environment observation / event alert'), a target ('active session'), and concrete examples. The caveat 'Does not advance the step count' distinguishes it from the step-advancing sibling execute_step, making the tool's role unambiguous.

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?

Provides clear context for when to use the tool: asynchronous environment notifications, background alerts, customer orders, and external world drift. It implies a contrast with step-advancing tools via the 'does not advance the step count' statement, though it does not explicitly name alternative tools or list when-not-to-use conditions.

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