set_app

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

With no annotations present, the description carries the behavioral burden. It discloses the key side effect (filtering/delivery restricted to the active app), explains null/None as 'no app', and mentions the registration prerequisite. Persistence details and output are not discussed, but they are minor for a state-setting tool.

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 short sentences, each earning its place: action and effect, null-clearing behavior, and registration pointer. The most important information is front-loaded and there is 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?

For a single-parameter state setter, this is complete: it defines the parameter contract, explains the effect, tells how to clear the state, and routes the agent to the relevant sibling tool. The presence of an output schema covers return-value expectations, so no additional return information is needed.

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 schema alone says only 'app: string | null'. The description adds the essential semantics: the string must be a name registered in MockPost, null/None clears the active app, and register_app is the way to create such names. This fully compensates for the 0% schema description coverage on the only parameter.

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 names a specific verb ('Set'), the exact resource ('the active app'), and the behavioral consequence (incoming simulations and queries are filtered/delivered only to that app). It also refers to register_app, making its role distinct from the registration sibling.

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?

It clearly conveys when to use the tool: to scope event simulations and queries to a specific registered app. It explicitly points to register_app for registering apps. It does not exhaustively enumerate all when-not-to-use cases across siblings, but the context is strong.

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