es_list_indices

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

With no annotations, the description carries full burden. It implies a read-only operation by using 'List', and it discloses output components (document counts and sizes). Yet it lacks details on potential side effects, performance implications, or whether special permissions are needed, leaving some gaps.

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 two concise sentences, front-loaded with the main action and purpose. Every sentence contributes: the first specifies what it does, the second explains when to use it. No fluff or redundancy.

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 list tool with zero parameters and an output schema present, the description is complete. It states the output (document counts and sizes) and gives a clear use case, so the agent has sufficient context to invoke it correctly.

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 tool has zero parameters, so the schema already provides complete coverage (100%). According to the rubric, a baseline of 4 is appropriate when there are 0 params, and the description adds no conflicting or redundant information.

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 clearly states the action ('List all Elasticsearch indices') and additional specifics ('with document counts and sizes'). It distinguishes itself from sibling tools like es_get_mapping and es_sample_data by focusing on listing indices rather than retrieving mappings or sample data.

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?

It provides a clear use case: 'Use this to discover available download/package data indices.' This guides the agent toward discovery scenarios. However, it doesn't explicitly mention alternatives or when not to use it, so it falls short of a 5.

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