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

The readOnly, non-destructive, closed-world annotations already establish the safety profile. The description adds useful context beyond annotations: it requires a first-time login, defines vaults as locked savings from recurring Mobile Money deposits, and enumerates the returned fields including status and next due date. It does not mention ordering or pagination, but for a no-parameter read-only listing this is strong context.

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 tightly written sentences: the first front-loads the user scope and authentication prerequisite, the second names the resource and lists the returned fields. Every element earns its place, and there is no redundant restatement of the title.

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?

Given zero parameters, read-only annotations, and no output schema, the description provides the key domain context and explicitly lists what the returned vault data includes. It is close to complete for this simple tool, though a brief note about ordering or whether all vaults are returned would remove the remaining ambiguity.

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?

The tool has zero parameters, so there is no parameter semantics to document. Baseline 4 is appropriate; the description does not need to explain inputs because none exist.

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 identifies the resource as the connected user's Tchin savings vaults, and explains what a vault is (locked savings fed by regular Mobile Money deposits). It also lists the exact fields shown, which makes the purpose concrete. It does not explicitly differentiate itself from sibling account-listing tools, which keeps it from 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 establishes the user context (connected Tchin account, merchant or individual) and notes that login is requested the first time. However, it does not say when to use this instead of nearby tools like mon_compte, bilan_compte, or tchin_suivi, so usage is implied rather than guided.

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