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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safe-read profile is covered. The description adds genuinely new context by disclosing the return shape (CSV with symbol,name,index_code,index_name,is_main_index), which is valuable since no output schema exists.

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, zero padding, with the resource definition front-loaded ahead of the optional filter and the return format. Every clause carries information an agent can act on.

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 parameterless list tool with one optional filter, annotations covering safety and an inline statement of the returned columns, nothing further is needed for correct invocation. Absence of an output schema is fully compensated by the CSV column disclosure.

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% and the single optional parameter is fully documented, so the baseline is 3. The description's 'optionally search by name' restates what the schema already says without adding format or matching semantics.

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 (List) and resource (CSE market/sector indices), and names concrete instances (ASPI, S&P SL20, industry sub-indices) so an agent knows exactly what is covered. It does not explicitly distinguish itself from the closest sibling get_index_data, which is the only gap keeping this below a 5.

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 says the query parameter is optional and used to search by name, which is implicit usage guidance for the one parameter. It never states when to use this list tool versus get_index_data or screen_indices, so the agent must infer the boundary between them.

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