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

Annotations already declare read-only/idempotent/non-destructive, so the safety profile is covered, and the description still adds real behavior: drafts are ignored, currencies are summed without conversion, and a no-finalized-invoice case raises an error. The only missing piece is the error shape or empty-result handling, which is minor.

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-loads the summary contents, then appends caveats in a compact block with no filler. The lead sentence is long but every clause is load-bearing; only slight tightening would improve it.

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 output schema, the description fully enumerates the return fields (count, totals, dates, top line items with latest price, email count) and flags the error case, which is everything an agent needs to call and interpret it.

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% and the single parameter is documented as an exact match, so the description's "(exact company name)" merely restates the schema. Baseline 3 applies; no extra format or edge-case guidance (e.g. casing, whitespace) is added.

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 ("Summarizes the finalized invoices for one client") and enumerates exactly what the summary contains, so an agent can tell it apart from get_customer, get_balance, or get_revenue_summary without inspecting schemas.

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 usage contexts: "answer questions about a client" or "pick prices for their next invoice." It does not name explicit alternatives or when-not-to-use cases, but the intended situations are concrete.

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