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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description contributes the response shape (per-tool, day-by-day, limits and limit requests), which is real added context, but it does not say what happens when the person is unmatched or how the default month is resolved.

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?

It is a single sentence with no padding, and the subject (one person's month) is front-loaded. But the clause structure is tangled — 'each tool at the contract, day by day, their limit and their requests for more' — which costs clarity rather than saving space.

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?

An output schema exists, so return values need not be spelled out, and annotations cover safety. Still, for a reporting tool in a 50+ sibling set, the description leaves the default month behavior and the unmatched-person path underspecified, which are exactly the details an agent needs to call it correctly.

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 carries the burden. It does explain the non-obvious 'person' format (an email, or tool:id for unmatched people), which the schema does not. However, the 'month' parameter is never addressed — no mention of the YYYY-MM format or what a null default means.

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?

It conveys a per-person monthly view of tool usage against contract limits, which does separate it from org-wide siblings like coding_agent_spend or get_spend. But there is no clear verb, and 'each tool at the contract, day by day, their limit and their requests for more' is dense and ambiguous — an agent has to guess whether it returns usage, contract terms, limit requests, or all three.

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?

There is no explicit when-to-use guidance and no named alternative (e.g. vs. coding_agent_spend, month_end, or teams_and_people). The aside 'tool:id for someone not matched yet' hints that match_person may be a prerequisite, but that inference is left entirely to the agent.

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