decode_pan_type

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

Annotations already declare readOnlyHint, idempotentHint, and the description's 'README_ONLY' permission tag aligns. The description adds meaningful behavioral detail by revealing that the operation depends on the 4th character of the PAN, which is not visible in the 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 a single, focused sentence with no wasted words. The permission comment is redundant with annotations but does not significantly harm conciseness.

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 one-parameter read-only decoding tool with a complete schema, output schema, and annotations, the description is sufficient. An agent knows what it does, what input to provide, and has the output schema for the result.

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 coverage is 100% and the schema says '10-character PAN'. The description adds semantic value by stating the 4th character is the relevant part, giving an agent insight into how the pan parameter is interpreted.

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 ('decode') and identifies the exact resource and logic: 'PAN entity type from 4th character'. This makes the tool's purpose immediately clear and distinguishes it from sibling tools like validate_pan or decode_state_code.

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 implies this tool is for decoding entity type rather than validation, but it does not explicitly state when to prefer this over sibling tools like validate_pan or bulk_validate_pan. Usage context is inferable from the tool name and sibling list, but no direct guidance or exclusions are provided.

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