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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds real value beyond that by enumerating the returned fields (scheme name, NAV, NAV date, fund house, scheme type), which matters because no output schema exists. It stops short of noting data staleness or rate limits.

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?

Standard Args/Returns docstring layout is front-loaded with the core action, then input detail, then output detail. Slightly formulaic indentation, but every section carries information and nothing is redundant.

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's Returns block is necessary and present; it also fully documents the lone required input. Error behavior for invalid codes is unaddressed, but for a simple read-only lookup the definition is close to complete.

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 0% and the single parameter has no schema-level documentation, so the description carries the full burden. It defines what the parameter is (AMFI scheme code), gives a concrete example value, and tells the agent where to source valid codes.

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 (get) and resource (latest NAV of an Indian mutual fund) keyed on a named identifier (AMFI scheme code). This is clearly a data-lookup tool and is easily distinguished from the calculator and product-search siblings.

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?

Provides concrete context: the AMFI scheme code format, a worked example ('119598' for SBI Bluechip Direct), and pointers to where codes are found (mfapi.in, amfiindia.com). It does not name alternatives or state when not to use it, but the lookup scenario is unambiguous.

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