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

The annotations already establish that this is a safe, idempotent read operation, and the description adds useful context about returned statuses and fields such as net VAT due, due date, and HMRC receipt. It does not contradict the annotations, though it leaves ordering and full response shape unspecified.

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 purpose and returned fields are front-loaded, followed by a clear usage directive. The two sentences are dense but contain no redundant or filler content.

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 read-only listing tool with full parameter documentation and no output schema, the description gives enough information about what the result contains and why to call it. It is not exhaustive about response structure or ordering, but it covers the key decision-relevant details.

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 100%, so all four parameters are already documented in the input schema. The description does not add parameter semantics beyond the schema, making 3 the appropriate baseline.

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 uses a specific verb and resource: it says it lists the company's VAT return periods and their statuses. It also clarifies that this is the source of the period_id needed by the other VAT tools, which distinguishes it from VAT summary/calculation siblings.

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 explicitly says to use this FIRST when the user asks about VAT returns, outstanding quarters, whether a quarter was filed, or before calculating/locking/submitting. Those usage conditions are concrete and directly route the agent before related VAT actions.

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