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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds the CSV return contract (symbol, name, index_code, index_name, is_main_index) and optional name filtering, which are useful behavioral details beyond the annotations.

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 sentences with no wasted words. The description front-loads the core action and resource, then efficiently covers optional search behavior and the CSV output contract.

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 list tool with one optional parameter and no output schema, the description provides the essential invocation details: the resource scope, search behavior, and CSV columns. The only notable gap is sibling differentiation, which is captured under usage guidelines rather than missing invocation context.

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?

The input schema already provides full documentation for the query parameter with an example, and schema description coverage is 100%. The description repeats 'Optionally search by name' without adding new meaning, so the baseline of 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?

The description states a specific verb ('List') and a concrete resource ('CSE market/sector indices') with examples like ASPI and S&P SL20. This makes it clearly distinct from sibling tools like get_index_data or screen_indices, which focus on data retrieval or screening.

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?

No guidance is given on when to use this tool versus alternatives such as get_index_data or screen_indices. 'Optionally search by name' only clarifies the parameter's behavior, not the tool-selection context.

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