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

With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses the key behavioral trait that missing inputs fall back to documented defaults, and enumerates what the calculator evaluates for each scenario. Since this is a read-only calculation tool, there are no destructive side effects or auth requirements to disclose, and the description covers the meaningful computation behavior.

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 reasonably short and front-loads the purpose, but it contains redundancy: 'Run the IHT calculator: today vs April 2027 calculator:' repeats 'calculator' in a clunky way. The output list is useful, but the phrasing could be tightened without losing information.

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 that there is no output schema and no annotations, the description does a good job of stating what the calculator computes and how defaults behave. It does not describe the return format or units, but for a calculator with all optional parameters and clear computation scenarios, the description is largely sufficient for an agent to invoke it correctly.

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 the schema already documents all seven parameters in detail. The description adds no parameter-specific meaning beyond mentioning that missing inputs use defaults, which is already reflected in the schema defaults. Baseline 3 applies because the schema does the heavy lifting.

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 states the tool runs an IHT calculator comparing today's rules with April 2027 rules, and lists the exact computed outputs: estate today, estate from April 2027, tax-free allowance, and IHT under current rules. This is a specific verb with a specific resource and is not a tautology of the name or title. It also distinguishes itself from sibling calculator_describe by saying 'Run' rather than describe.

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 description provides clear context: the tool is for calculating IHT under current and future 2027 rules, so an agent can infer when to invoke it. However, it does not explicitly state when not to use it or mention alternatives such as calculator_describe, so it falls just short of full routing guidance.

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