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

Annotations already declare destructiveHint=true, readOnlyHint=false, openWorldHint=false. The description goes beyond them by disclosing a non-obvious failure mode — for account-linked parties only party_reference is mutable and other field updates will fail — plus the partial-update semantics ('only need to be sent if their value should change').

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?

Front-loads the one-line purpose, then the when-to-use condition, then required vs optional parameters, then the key constraint. Every sentence carries information and there is no filler.

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?

An output schema exists so return values need no explanation, and annotations cover the safety profile. Combined with 100% schema coverage and the explicit account-party constraint, an agent has everything needed to call it correctly.

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 already 100%, so the baseline is 3. The description adds real value on top: it defines party_identifier as a ref_uuid, reference, or entity_name, and clarifies that non-required fields are conditional partial updates. The enum and is_internal constraints live in the schema, so this is additive rather than duplicated.

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?

States a specific verb (edit/update) and resource (a party on a document), and the field-enumeration ('reference, entity type, entity name, address, or scope') makes it unambiguous. It is clearly distinguishable from siblings like update-document, create-document-party, and update-template-party.

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 explicit 'Use this tool when' clause gives a clear triggering condition (a party field on an existing document needs to change). It stops short of naming sibling alternatives such as create-document-party for adding a new party, so the agent must infer the add-vs-edit boundary.

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