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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so safety is fully covered. The description adds genuinely new lifecycle context — labels exist implicitly and are created via create_transaction/update_transaction — which explains why there is no create_label sibling. It stops short of any return-shape or ordering detail.

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 core action is front-loaded in the first clause, and the following sentences each add distinct value (definition, routing guidance, lifecycle). The middle sentence is dense and packs definition, example use cases, and a sibling reference together, slightly hurting scannability, but nothing is wasted.

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 one-parameter read tool with no output schema, the description covers purpose, taxonomy placement, routing, and creation lifecycle — everything needed to decide and call correctly. It doesn't characterize what a returned label object contains, but with annotations and a simple schema present that is a minor 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?

There is a single required user_id at 100% schema description coverage, so the schema carries the parameter semantics fully. 'Belonging to a user' reinforces the scoping but adds no syntax or format detail beyond what the schema states. Baseline 3 applies.

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 and resource ('Lists all labels belonging to a user') and immediately defines what a label is, distinguishing it from categories: free-form tags that span categories. It also names the sibling whose search already matches label text (list_transactions), so an agent can tell the tools apart without opening either schema.

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?

Gives an explicit when-to-use condition: 'check here when a pull together my work expenses style ask has no matching category,' and names the alternative path (list_transactions search matches label text). It also covers the when-not case by pointing to categories as the primary taxonomy.

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