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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, covering safety. The description adds the behavioral detail of no AI credit cost and availability on every plan, which is valuable context beyond annotations. It does not contradict annotations. Some additional details (e.g., rate limits or exact response shape) are absent, but the annotations carry the safety profile.

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?

The description is compact: two sentences, the first states purpose and the second gives usage triggers. Every sentence earns its place, and it is front-loaded with the core purpose. No fluff or redundancy.

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?

The tool has an output schema (present in context), so return values are already defined. The description covers what the tool returns, when to use it, and its cost characteristics. For a read-only, parameterless tool, this is fully complete – an agent has everything needed to decide when and how to invoke it.

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 tool has 0 parameters, so the description need not explain them. The schema already fully documents the empty parameter set. Baseline for 0 params is 4, and the description doesn't need to compensate. The description correctly avoids inventing parameters.

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 clearly states the tool returns the user's subscription tier and per-tier quotas (channels, storage, AI credits, posting). The verb 'Return' and resource are specific. It does not explicitly differentiate from the sibling 'get_plan', but the added 'limits/quotas' detail provides some distinction. A clear, unambiguous purpose.

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?

The description explicitly states when to call it: when the user asks about plan/limits, and proactively before potentially blocked actions, with concrete examples (before create_post_draft when aiCalls is low, before schedule_post on FREE, before connect_channel near cap). It also notes availability on every plan with no AI credit cost. This is exemplary usage guidance with exclusions and alternatives implied.

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