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

Annotations already declare a destructive mutation (readOnlyHint=false, destructiveHint=true). The description adds meaningful operational context beyond annotations: partial-update behavior and the requirement to pair participants with splitConfig when changing amount or participants. It does not detail authorization or field replacement effects, keeping it from a 5.

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?

Two sentences with zero waste, and the partial-update constraint is front-loaded before the conditional coupling rule. 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?

The description covers the most error-prone part of the update (amount/participants/splitConfig coupling) but is incomplete for a 9-parameter nested mutation with no output schema and low schema description coverage. Guidance on updating other fields, permissions, and side effects is missing.

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 11%. The description adds some meaning for amount, participants, and splitConfig coupling, but leaves transactionId, type, currency, categoryId, description, and transactionDate undocumented. It fails to compensate for the very low schema coverage.

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: 'Update fields of an existing group transaction.' It is clear what the tool does, but it does not explicitly differentiate itself from siblings like update_personal_transaction or mention alternatives, so it falls short of a 5.

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 gives explicit partial-update guidance ('Only send the fields to change') and a dependency rule for amount/participants changes, referencing create_group_transaction for split rules. It lacks explicit when-not-to-use or alternative routing guidance, but the context is clear.

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