Fund NAV

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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is fully covered. The description adds the pointer to the source tools for counter_id but says nothing about return format, units, or freshness beyond 'latest'.

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?

Two short sentences with no waste, and the core action is front-loaded ahead of the parameter-sourcing hint. Appropriate size for a simple single-purpose lookup tool.

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 trivial read-only single-param lookup whose safety is covered by annotations and whose parameters are fully documented in the schema (and there is no output schema to explain), the description carries enough to call 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 description coverage is 100%, so both parameters are already documented in the schema, including the same 'Obtain it from fund_hot or fund_list' note. The description adds no syntax or format detail beyond that, 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?

States a specific verb and resource ('Get a fund's latest net asset value (NAV)'). The qualifier 'latest' implicitly distinguishes it from sibling tools like fund_nav_history and fund_nav_range, though it does not name them explicitly.

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 description tells where to source the required counter_id (fund_hot / fund_list), which is useful context, but gives no explicit when-to-use guidance or contrast against the related NAV siblings. Usage is left implied by the word 'latest'.

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