get_index_fields

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does well by explaining the default index behavior ('stats-*'), the filtering capabilities, and the purpose of field discovery. However, it doesn't mention potential rate limits, authentication requirements, or what the output format looks like (though there's no output schema).

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 efficiently structured with clear front-loading of the core purpose, followed by usage guidelines and important warnings. Every sentence earns its place by providing specific guidance or context without redundancy. The warning section is appropriately highlighted with emoji and capitalization.

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 tool with 4 parameters, 100% schema coverage, and no output schema, the description does well by explaining the tool's purpose, usage context, and behavioral constraints. However, it doesn't describe what the return values look like (field format, structure, or examples), which would be helpful given the lack of output schema.

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 baseline is 3. The description adds value by explaining the purpose of field filtering ('optional filtering by field name and type'), providing context about when to use the index parameter (only when explicitly requested), and giving examples of type filters ('keyword fields for exact matches or text fields for full-text search').

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 verb ('Get all fields') and resource ('from an Elasticsearch index'), specifies the optional filtering capabilities, and distinguishes this tool from its siblings by focusing on field discovery rather than data retrieval or analysis. It explicitly mentions discovering available fields, their types, and correct field names.

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 provides explicit guidance on when to use this tool ('when you need to discover available fields... before constructing queries') and when not to use it (⚠️ IMPORTANT warning about not specifying the index parameter unless explicitly requested). It also explains the specific use cases like being unsure about field names or looking for fields with specific types.

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