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

Annotations cover the safety profile (readOnly, non-destructive), but the description adds substantial context beyond them: coverage scope, publication lag, excluded fund types, and the critical caveat that the reported weight is not a share of the company. This prevents misreading of the returned numbers.

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 dense sentences that are front-loaded with the core action and input format, followed by scope caveats and the sibling pointer. Every sentence carries information, though the block is on the heavier side.

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 compensates by enumerating the returned row fields (fund, manager, quantity, SEK market value, weight) and defining what each means. An agent has everything needed to call and interpret the tool correctly.

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 offset, maxResults, periodEnd and the ticker format. The description still adds value by clarifying the MIC:TICKER convention and the fallback behavior for a bare ticker, though most of the ticker semantics are also present in the schema.

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 (European fund positions in a given listing) and immediately distinguishes itself from GetFundsHoldingStock for US-registered funds and from SEC-filing data. An agent can identify this tool's domain without opening 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?

Explicitly names the alternative route ('For US registered funds use GetFundsHoldingStock'), states the required input format MIC:TICKER, and sets expectations about coverage and exclusions (Swedish UCITS only, special funds excluded, ~2-month delay). This is when-to-use and when-not in one place.

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