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

Annotations already provide readOnlyHint and idempotentHint. The description adds useful behavioral context: the surtax-only scope, the input precondition, the €50,000 trigger, and a warning not to add this to the sibling tool. It does not describe the exact response format, but that is minor for a one-parameter calculation tool.

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 compact and front-loaded: it establishes the standalone surtax scope, gives the input condition and threshold, routes to the sibling for total tax, warns against double-counting, and cites the legal source. Every element earns its place.

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 calculation tool with one required parameter and no output schema, the description is complete. It provides input semantics, threshold, relation to the sibling tool, a misuse warning, and the legal source, leaving no critical ambiguity for an agent deciding whether and how to call it.

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?

Although the schema documents the parameter at 100%, the description adds decisive meaning beyond the label 'Plus-value nette imposable (€)'. It clarifies that the value must already be net of holding-period allowances and that the €50,000 threshold determines applicability.

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 tool as computing the standalone additional surtax on a net taxable real-estate capital gain above €50,000, using a bracketed scale. It explicitly contrasts this with the sibling fiscal_plus_value_immobiliere, so an agent can tell them apart immediately.

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 states exactly when to use this tool: when the net taxable gain is already computed after holding-period deductions. It also gives an explicit alternative for the total disposal tax and warns against double-counting, which is strong usage guidance.

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