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

Annotations already declare destructiveHint=true and idempotentHint=true, but the description adds real value beyond them: irreversibility ('this cannot be undone') and the account-level business rule that the final UPI ID is protected. It does not mention permission requirements or what the response returns, but with the output schema present that is acceptable.

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?

Three tight sentences, front-loaded with the action, then the guardrail, then the consequence and alternative. No filler or repetition of the title.

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 destructive single-parameter mutation with an output schema, the description covers the safety profile, the key constraint, and an alternative path. The only real gap is the meaning/format of the 'id' argument, which the schema leaves undocumented.

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 0% for the single required parameter 'id'. The description adds nothing about whether 'id' is the internal integer identifier or the UPI handle string, which is a genuine ambiguity given a UPI ID is normally a text handle. The description does not compensate for the coverage gap.

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?

Specific verb plus resource ('Remove a UPI ID from the account'), which cleanly separates it from add_upi_id, update_upi_id, list_upi_ids and set_default_upi_id. An agent can identify the operation without opening the schema.

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 states a hard precondition ('the last one cannot be removed') and points to an alternative behavior when removal is undesirable ('switching it off instead keeps it'). It does not name the sibling tool that performs the switch-off, so routing is implied rather than explicit.

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