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

Goes well beyond the annotations: it discloses plan gating (Pro feature, 14-day trial), the exact failure mode on Free (refused with a message pointing at billing), the auto-downgrade when Pro days lapse, that turning it off always works, required roles, and the return value. None of this is recoverable from readOnlyHint/idempotentHint alone.

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?

Front-loads the core behavior and its complement, then layers exemptions, plan gating, and permissions in a logical order. It is dense but nearly every clause carries a fact an agent needs; the billing/plan sentence is the only one that could be trimmed slightly.

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 three-parameter idempotent toggle with no output schema, the description covers the state transition, the failure case, the downgrade behavior, the permission model, and the returned shape ('the app's settings with alwaysOn as it now is'). Nothing required to call it correctly is missing.

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% and each parameter is already documented, including the true/false semantics of alwaysOn. The description restates the boolean meaning but adds no syntax, format, or constraint information beyond the schema, 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 and resource (set always-on for a Streamlit app) and immediately defines both directions of the toggle. It also explicitly distinguishes itself from fastero_run_streamlit_app, so an agent can tell the two apart without inspecting 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?

Gives a clear when/when-not: use this to keep an idle app warm or let it sleep, and it explicitly says 'It does not start a stopped app: fastero_run_streamlit_app does.' The named alternative removes any ambiguity about which sibling to call.

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