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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description is free to focus on semantics, which it does: results are broken down by currency and by downstream outcome rather than a single scalar. It also discloses the identity constraint that the current user's id cannot be looked up, which is real behavioral context not in the annotations. It stops short of describing grouping limits or ordering.

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?

Four tight sentences, each with a distinct job: what it computes, when to prefer it, the current-user rule, and the date format. The aggregation scope is front-loaded and nothing is repeated without purpose.

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?

For a three-parameter read-only aggregate with no output schema, the description covers purpose, alternative, identity resolution, and date format, which is nearly everything needed to invoke it correctly. Minor gaps remain on result shape granularity (e.g., whether groups are bounded or ordered) and on the unusual idempotentHint=false for a read operation.

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 coverage is 100%, so the schema already documents all three parameters including the default-to-current-user behavior for approver_id. The description reinforces the omit-approver_id rule and the YYYY-MM-DD format but adds little syntax or meaning beyond what the schema states, so the baseline of 3 applies.

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: total up the value of approval requests a person APPROVED in a date range, with the aggregation dimensions named (by currency, by what later happened). This clearly separates it from listing siblings such as list_approval_requests.

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 concrete trigger questions ('how much did I approve this month', 'what did the CFO sign off on in Q1') and explicitly excludes the alternative path of listing every request and summing manually. It also routes the agent to search_team_users for any approver other than the current user.

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