Look up published sector classifications

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

With no annotations provided, the description carries the behavioral disclosure burden. It transparently reveals that out-of-universe instruments return unmatched rather than guessed, states the approximate universe size, and explains the no-argument vocabulary response. It lacks detail on return shape, but the non-judgemental, read-only nature of the operation is well conveyed.

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?

The description is three sentences with no filler. It front-loads the core purpose, immediately follows with the key limitation that differentiates the tool, and ends with a practical usage tip. Each sentence earns its place.

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 look-up tool with two optional parameters and no required inputs, the description covers what an agent needs to decide when to call it and what to pass. It even explains the no-argument call for exploring the vocabulary. The only gap is the exact shape of the returned sector assignments, but the 'resolves to sector' phrasing and unmatched behavior make the expected outcome reasonably clear.

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 schema already documents the isins and symbols parameters, including examples. The description adds only a high-level 'by ISIN or trading symbol' mapping and the no-argument behavior, which is useful but not a substantial addition 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 uses a specific verb-resource pair: 'Resolve instruments to NSE's macro-economic sector by ISIN or trading symbol.' It clearly distinguishes itself from sibling tools by emphasizing it is an official published classification, not a judgement call, which prevents confusion with search or quote tools.

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: use it for official NSE sector classification of Nifty Total Market constituents, and explicitly warns that anything outside that index returns unmatched rather than guessed. It also provides a concrete invocation strategy ('Call with no arguments'), though it does not explicitly name alternative tools or state when not to use it.

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