Fund Position NAV

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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds useful behavior the annotations don't: the auth requirement and the fact that the window is relative (with a server default when both window params are omitted).

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, front-loaded sentences: purpose first, then prerequisites, then parameter guidance. No filler, and each sentence carries actionable content.

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 read-only, single-resource history tool with a fully documented schema, this covers purpose, auth, sourcing of the required id, and window semantics. With no output schema it could say a bit more about what the NAV history payload contains, but nothing needed to call it correctly is missing.

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 the baseline is 3, and the description goes a step further by naming the source tool for counter_id and stating that month_before or year_before governs the window. This adds invocation-level meaning beyond the schema field descriptions, though it slightly diverges from the schema's own sourcing hint (fund_hot/fund_list).

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?

The description states a specific verb and resource ("Get a held fund's NAV history") and scopes it to a relative window, which distinguishes it from the generic fund_nav_history/fund_nav_range siblings by narrowing to held positions. It stops short of naming those siblings explicitly, so the differentiation is implicit rather than spelled out.

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?

It gives concrete context: auth is required, counter_id comes from fund_position_overview, and the caller should set month_before or year_before. That is enough to invoke it correctly, though it never states when to prefer a different tool (e.g., the generic fund_nav_history) over this one.

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