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

Annotations already declare read-only, idempotent, closed-world behavior, so the description's added value is the disclosure that figures are computed server-side from live Fortnox data and aggregated over all pages. That tells the agent the output is current and complete, not a cached or truncated page. It stops short of explaining how partial periods or missing due dates are handled.

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?

Three short sentences, front-loaded with the core definition before the example and the data-source note. The API URL is arguably noise for an agent, but nothing else is wasted.

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 description needn't explain return shape; it covers purpose, data origin, freshness, and an illustrative query. The only real gap is that it never mentions the date/weeks defaults or absent-argument behavior, which the agent must get from the schema.

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%, and the two parameters (date, weeks 1–26 with defaults) are fully documented in the schema. The description adds only an oblique hint in the example question ("sex veckor") and no format or range detail beyond the schema, so baseline 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?

"Bokfört banksaldo plus förfallande in- och utbetalningar vecka för vecka" states a specific computation, its inputs (booked balance + due payments) and its output granularity (weekly). An agent can distinguish this forecast tool from aging/reporting siblings like get_payables_aging or get_receivables_aging without reading the schema.

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 example question ("Räcker pengarna de närmaste sex veckorna?") implies the liquidity-planning scenario in which to use it, but there is no explicit when-not guidance or named alternative among the ~90 siblings. Usage is inferable rather than stated.

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