validate_pan

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

Annotations already provide readOnlyHint and idempotentHint, so there is no contradiction. The description adds useful behavioral details beyond annotations: spaces and hyphens are stripped automatically, the PAN check character is not publicly verifiable, and the result comes in a standard envelope.

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 well-structured with Purpose, Usage, Args, Returns, and Notes sections. It is concise, front-loaded with the key operation, and each part provides distinct value without redundant fluff.

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?

Given the single parameter, rich annotations, and existing output schema, the description covers everything needed to invoke the tool correctly. The note about the check character limitation is an important extra that prevents customer assumptions.

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 schema already covers type, length, and allowed spaces/hyphens, so the baseline is 3. The description adds value with a concrete example and the automatic stripping behavior, which clarifies how the input should be supplied.

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 and resource: 'Validate Indian PAN format and decode entity type from the 4th character.' It clearly distinguishes itself from the sibling tool 'decode_pan_type' by combining validation with entity type decoding. There is no ambiguity about what the tool does.

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 explicitly says to use the tool when normalizing tax identity records in KYC, invoicing, or vendor onboarding. It does not mention alternatives or when not to use it, which is a minor gap, but the context is clearly stated.

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