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

With no annotations, the description carries the full burden and does so: it discloses the write semantics, the silent partial-write failure mode (rest-of-world flag set, country list empty), the downstream symptom (bare FAILED_PRECONDITION from start_rollout), and the misleading state report from get_setup_state. It also states what the tool does not do ("Does not publish anything"), which is exactly the kind of non-obvious trait an agent needs.

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?

Purpose and the critical constraint are front-loaded before the failure detail, and nearly every sentence carries actionable content. The failure is described twice (validator refusal plus the stripped FAILED_PRECONDITION symptom), which is slightly redundant but justified by how non-obvious the trap is.

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?

Covers the hard parts for a 7-parameter mutation with no annotations and no output schema: the worldwide-launch recipe, the empty-list trap, and user confirmation. It leaves open whether an existing country list is replaced or merged on repeat calls, and says nothing about the response shape beyond the failure path.

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 coverage is 100%, so the baseline is 3; the description goes beyond the schema by explaining the interaction between targeted_countries and target_rest_of_world, including the degenerate combination that silently breaks rollouts. It does not touch notification_message or the id-confirmation params, which the schema already covers.

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 and resource ("Set which countries/regions a release track serves") and names its role in the workflow ("the precondition for a track's first rollout"), which separates it from update_store_settings, create_release, and start_rollout. An agent can tell instantly what it mutates and where it sits in the sequence.

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?

Explicitly says when to call it (before a track's first rollout), what NOT to do (target_rest_of_world="true" alone), the exact recipe for a worldwide launch, and the human-in-the-loop rule ("Ask the user which countries; never pick for them"). It also clarifies scope boundaries by naming start_rollout as the downstream step this tool does not perform.

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