explain_delivery_failure

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds value by disclosing what the caller gets back (a plain-English explanation plus next steps), which is important since no output schema exists.

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?

One sentence, zero filler, with the purpose and output form front-loaded. Nothing is redundant with the name or schema.

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 read-only, single-parameter lookup with no output schema, the description covers purpose, parameter domain, and the shape of the result. It stops short of examples of accepted code formats, which is the only remaining gap.

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 0% and the schema only types 'code' as a non-empty string, so the description carries the burden. It does narrow the parameter's domain to Meta/WhatsApp delivery or template error codes, which is meaningful, but it gives no format detail (numeric vs string, code families) or examples, so it only partially compensates.

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 (explain), a specific resource (Meta/WhatsApp delivery or template error code), and even the output form (plain English with next steps). This cleanly separates it from all siblings, which are lookup, CRUD, or send operations rather than diagnostics.

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 phrase 'delivery or template error code' implies the triggering context, so usage is inferable. However, there is no explicit statement of when to call this versus other troubleshooting paths, nor any exclusions, and no sibling is named as an alternative.

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