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

The description goes well beyond the readOnlyHint/openWorldHint annotations by disclosing that the call does not consume allowance and by specifying exact handling for action_required results, including relaying links and offering retry. It also warns against silently skipping the calculation, which is valuable behavioral contract for an agent.

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?

Three sentences, each carrying essential information: what the tool returns, the key side-effect (no allowance consumption), and the required action on action_required. There is no filler and the purpose is front-loaded.

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 output schema, the description does enough by naming the result categories (usage history, endpoint/source breakdown, action_required) and prescribing the retry/relay behavior. It stops short of full field-level detail, but for an agent selecting and invoking the tool this is sufficient.

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 description coverage is 100%, so the from/to parameters are already fully documented as optional UTC dates. The description adds no additional parameter meaning, so the high-coverage baseline of 3 is appropriate.

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 uses a specific verb ('Returns') with a clear resource ('signed-in usage history') and adds a distinguishing detail ('endpoint/source breakdown'). This differentiates it from sibling tools like get_account_access or get_checks without needing to inspect 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?

Usage context is implied: this is the tool for signed-in usage history and endpoint/source breakdown. However, it does not explicitly state when to choose this over sibling tools or mention any exclusions, so the guidance is adequate but not fully explicit.

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