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

The readOnlyHint annotation already establishes that this is a safe read operation. The description adds useful behavioral context by stating that the account is implicit via the transport API key and that it returns recent movements, but it does not explain how far back movements go, whether results are paginated, or what format the balance and movements take.

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 description is a single, front-loaded sentence with no redundant or filler language. It immediately states what is returned and how the account is scoped.

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 simple zero-parameter read tool with no output schema, the description is largely complete: it identifies the implicit account source and summarizes the return content. It could be slightly more complete by describing the movement window or response shape, but the essential context is present.

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 input parameters, so the parameter semantics baseline is 4. The description correctly reinforces that no account identifier is needed because the API key determines the account, which is consistent with the empty schema.

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: it returns the account balance and recent account movements. It also clarifies that the account is selected by the API key carried by the transport, which distinguishes it from tools that take explicit company or document identifiers. It does not explicitly name or contrast with the sibling tool top_up, so it is clear but not maximally differentiated.

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 intended use is implied: an agent can infer this is the tool for checking the current balance and recent movements of the authenticated account. However, there is no explicit when-to-use guidance, no exclusions, and no mention of top_up or other alternatives for account-related operations.

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