Mutual fund NAV history

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

Annotations already establish that the tool is read-only and idempotent. The description adds useful behavioral context beyond those: results are ordered oldest first, dates are ISO and optionally bound the series, and the data originates from mfapi.in/AMFI, which hints at possible external-source limitations.

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 tight sentences: the first front-loads the core function and ordering, the second adds date bounds and source provenance. There is no filler or repetition of schema details.

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 simple read-only series tool with rich annotations and fully documented parameters, the description covers the essential behaviors: what is returned, ordering, optional date bounds, and data source. No critical invocation details are 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 coverage is 100%, with all three parameters already described clearly, including the inclusive ISO date semantics for start and end. The description echoes the date-boundary concept but does not add material new parameter meaning beyond 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?

The description states a specific resource ('Historical NAV series for one scheme') and a clear behavioral detail ('oldest first'). This clearly distinguishes it from sibling tools like mf_search_schemes and mf_scheme without needing to inspect them.

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 gives clear context for when to use the tool: retrieving historical NAV data for a single scheme, optionally constrained by date range. It does not explicitly name alternatives or state exclusions, but the intended use is evident from the first sentence.

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