pi_models

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

With no annotations, the description carries the behavioral burden and does so well: it states this is a read from the live catalog ('actually reach right now') and explicitly denies side effects. It could add error/availability behavior or auth expectations, but the core read-only, no-task traits are clear.

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 tight sentences, front-loaded with the main action and output fields before the usage directive. Every sentence contributes either scope, use case, or a side-effect exclusion; 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?

Given the simple one-optional-parameter input and no output schema, the description is complete: it describes the returned model attributes, the purpose, and the non-mutating behavior. An agent can call it correctly without additional context.

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 already documents the only parameter with 100% coverage, so the description need not compensate; it stays at the baseline. The description does not add extra semantic detail beyond the schema's 'Optional fuzzy filter' with examples.

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 opens with a specific verb and resource ('List the models pi can actually reach right now') and enumerates the return fields, making the tool's function unmistakable. It also ties itself to pi and pi_reply, which separates it from the session/task siblings 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?

It explicitly tells the agent when to use it: to pick `model` and `thinking` values for `pi` / `pi_reply`. The closing phrase 'Starts no session, runs no task' also signals when-not to use it, distinguishing it from pi_send, pi_running, and pi_sessions.

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