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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds real context beyond that: what it returns (likely routes with the 2026 income figure and quick checks) and an explicit 'not legal advice' caveat that explains why escalation exists.

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?

Three sentences, front-loaded with what the tool does, then what it returns, then the disclaimer/escalation. Dense and largely waste-free, though the parenthetical purpose list partially duplicates the schema enum.

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?

With no output schema, the description carries the return-value burden and does so ('likely routes with the 2026 income figure and quick checks'). The only notable gap is that it does not mention all six parameters are optional, so an agent may not realise it can call with partial facts.

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 every parameter including enums and the boolean flags is already documented, making 3 the baseline. The description enumerates the facts it consumes (purpose, EU citizenship, partner/family in Spain, income, family members) but adds no format or edge-case guidance beyond the schema, and omits currently_in_spain_legally entirely.

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?

States a specific verb and resource: an 'orientative first look at which Spanish visa or residence route fits a person', scoped to a defined set of input facts. It also names the sibling tools it is not (personal_visa_assessment, request_consultation), so an agent can distinguish it from spain_visa_requirements and the other siblings without opening any schema.

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?

Explicitly frames this as a 'first look' and routes the agent onward when a real answer is needed: 'for a real answer offer personal_visa_assessment ... or request_consultation'. It gives clear escalation context but does not differentiate from spain_visa_requirements or schengen_90_180_calculator, which remain inferable only from their names.

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