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

Annotations already declare readOnly, idempotent, and non-destructive, lowering the bar. The description adds genuinely useful behavioral context beyond them: the returned balance is the pool that generation tools spend, and for team members it is the team's shared balance, which changes how the agent should interpret the number.

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 sentences, no filler. The purpose is front-loaded and the invocation condition follows immediately, so the most important facts land first.

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?

With no input parameters and no output schema, the description carries the full burden and mostly succeeds: it names the resource, the trigger, and the interpretive nuance. It stops short of describing the shape of the answer (numeric balance, currency, team context already covered), a minor gap for a trivial read tool.

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?

Zero parameters, so the baseline of 4 applies; there is nothing for the description to compensate for on this dimension.

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?

Specific verb+resource ('Show the user's available Metodic credits') paired with a clarifying definition of what credits are and which sibling tools consume them. It even disambiguates whose balance is returned (personal vs. team-shared), so an agent can distinguish it from the many generate_* siblings without opening a schema.

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 an explicit trigger set: user asks about 'credits, cost, or whether they can afford a generation.' That is clear context for invocation, though it offers no when-not guidance or named alternative (largely unnecessary here since no sibling returns a balance).

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