add_party_email_address

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

Annotations are minimal (readOnlyHint=false, destructiveHint=false), so the description carries the burden. It adds that the operation is atomic and uses a single PUT to Capsule, which provides some insight. However, it does not disclose error handling, idempotency, or whether duplicates are allowed. Still, it adds meaningful context beyond annotations.

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 two sentences: the first states the action and a technical detail (atomic PUT), the second provides usage guidance. It is front-loaded, no filler, and every sentence earns its place.

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 low schema coverage, no output schema, and minimal annotations, the description should cover more: no explanation of return values, no parameter details, and no error scenarios. It is adequate for purpose and usage but incomplete for a fully self-contained description.

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 only 33% (only 'type' has a description). The description does not elaborate on any parameter; it doesn't explain 'partyId' or 'address', nor does it provide examples. Given low coverage, the description should compensate but fails to add any parameter meaning.

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 action ('Append a single email address to a party'), specifies it's atomic, and explicitly distinguishes it from the sibling tool update_party.emailAddresses by explaining when to use each. This provides specific verb+resource+scope with differentiation.

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 gives explicit guidance: 'Use this instead of update_party.emailAddresses when you want to add exactly one entry; the bulk array on update_party is append-only and won't replace.' It clearly states context but does not mention other alternatives like add_party_address, which are for different resource types, so it's sufficiently focused.

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