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

Annotations already declare readOnly/idempotent/non-destructive, and the description still adds rare, decision-critical behavior: days are computed server-side against current UTC, expired rows are not pruned so the sign must be checked, and utilization is a TYPE-level monthly aggregate rather than per-commitment. That disclosure prevents an agent from misreporting a commitment as unused.

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?

Front-loaded with the purpose and ordering before the caveats, and every sentence carries non-redundant information about either data provenance or correct interpretation. It is dense but not padded, though the final threshold sentence is slightly long-winded.

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 schema, no output schema, and a zero-parameter signature, the description must carry the entire interpretation burden — and it does, covering ordering, sign semantics, staleness of expired rows, and the true granularity of the utilization figure.

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 is 4. The description spends its space on return-field semantics (days_until_expiration, latest_utilization_percentage) instead, which is the correct use of the budget here.

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?

States a specific verb and resource ('List this account's Reserved Instance / Savings Plan / Azure Reservation commitments'), scopes it to one account, names the key field returned, and specifies ordering ('soonest-first'). An agent can distinguish this from get_cost_entries or list_commitment_utilization immediately.

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 clear context for acting on results: the 30/14/7/1-day thresholds and 80% cutoff are the right flags 'for consistency with what a subscribed channel already receives', and it points at list_commitment_utilization as the source of utilization data. It stops short of an explicit when-not or a stated alternative tool for the same question.

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