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

Annotations already declare readOnlyHint=false, destructiveHint=true, and openWorldHint=false, so the safety profile is known. The description adds the partial-update contract, which is valuable behavior beyond the schema, but it never acknowledges the destructive hint or says whether omitted fields are preserved or cleared.

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 short sentences, zero filler, with the core action front-loaded and the critical partial-update rule immediately after. Nothing here is padded.

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 mutation across 9 parameters with 11% schema coverage and no output schema, this description is far too thin. It omits field semantics, permission expectations, and the consequence of the flagged destructive behavior, so an agent could call it correctly in shape but not confidently in effect.

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?

Nine parameters with schema description coverage of only 11% (essentially just transactionDate's 'YYYY-MM-DD'), so the description must carry the load. It names no parameter, no type or format expectations, and does not explain the enum values for 'type' or the uuid requirements, leaving the agent dependent on raw schema shapes.

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 ('Update') and resource ('fields of a personal transaction'), so the operation is unambiguous. It does not, however, differentiate itself from the sibling update_group_transaction or explain what 'personal' vs 'group' means in this context.

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?

'Only send the fields to change' is a genuinely useful usage instruction that establishes partial-update semantics and steers the agent away from a full overwrite. It says nothing about when to use this tool versus update_group_transaction or create_personal_transaction, so routing guidance is only implied.

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