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

Annotations already declare readOnlyHint and destructiveHint, so no contradiction. The description adds useful behavioral detail (settled spend, breakdown by counterparty/rail, optional time window), which goes beyond what annotations provide, but does not mention auth needs or rate limits. This is balanced given the annotations cover safety.

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?

A single, front-loaded sentence that covers the resource, breakdown, and optional window without waste. It is appropriate for a read-only tool.

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 an output schema present, the return values are covered. The description is complete for the tool's basic purpose but lacks parameter semantics and usage differentiation; however, given the optionality and read-only nature, its gaps are not severe.

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 0%, so the description must compensate for unclear parameters. It hints at the optional time window (since), but signerId and companyId remain unexplained, and there is no guidance about what they represent or when to use them.

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 and resource ('read an agent's settled spend'), and explicitly mentions the breakdown by counterparty and rail with an optional time window. This clearly distinguishes it from sibling tools like card_get_card_spend or read_transactions.

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?

No explicit guidance is given on when to use this tool versus alternatives such as card_get_card_spend or account balance tools. The description only states what it does, not when to prefer it or what it is not meant for.

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