Get usage and spend

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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered. The description goes further by disclosing what the report contains, including non-obvious content like budget remaining and running video jobs, and the word 'estimated' signals that the figures are approximations rather than billed amounts.

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 dense sentence that front-loads the purpose and then lists the report contents without filler. It is appropriately sized, though the trailing list of returned items is somewhat enumeration-heavy for a tool whose output schema already exists.

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 shape need not be spelled out, and the description still names the period options and the scope implied by 'this session'. What is missing is any note on data coverage or freshness limits (for example whether it reflects only this server's usage), which would matter for a spend-reporting 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?

Schema description coverage is 100%, so both parameters are already fully documented, including the default and max for 'recent'. The description merely restates the period values that the schema enumerates, adding no new syntax, defaults, or interpretation guidance.

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 ('Report estimated spend') and enumerates the dimensions of the report (by model and tool, budget remaining, recent calls, running video jobs). It is clearly distinct from most siblings, but it never draws the boundary against the closest sibling, estimate_cost, which an agent could easily confuse with it.

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?

The description implies the tool's use for inspecting accumulated spend and activity, and the period parameter hints at granularity choices, but there is no explicit when-to-use guidance nor any statement of when another tool (estimate_cost for projections, get_config for settings) should be preferred.

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