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

Annotations already declare a safe, idempotent read. The description adds real behavioral value beyond them: figures are rounded indicatively to the nearest 1,000 USD, are non-binding until a pre-check, and exact amounts require requesting the breakdown via quoteRequestUrl. It does not discuss caching, latency, or failure modes, so a 4 rather than 5.

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 the core verb and resource, then output contents, then the comparison fallback and pricing caveats. Dense but every clause carries information; the programme enumeration is somewhat redundant with 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?

Despite an output schema existing, the description usefully summarizes what is returned and, importantly, supplies the eligibility and non-binding-pricing context an agent needs to answer cost questions responsibly. Nothing material for correct invocation appears to be missing.

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 family structure, the programme enum, and language; the baseline is 3. The description reinforces the programme semantics ('without program compares all 9 programmes') and lists programme keys, but adds little syntax or format detail the schema does not already carry.

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 — answering 'how much citizenship by investment or a second passport costs' and comparing programmes by total cost — and enumerates the exact output components (government contribution, investment, fees, total in USD, eligibility, processing time). An agent can immediately distinguish this from list_cbi_programs or request_cost_breakdown_link.

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?

Clearly states the selection condition: 'With one programme it returns that programme; without program it compares all 9 programmes', plus the caveat that figures are indicative and binding only after a pre-check (steering the user toward the cost-breakdown sibling). No explicit when-not or named alternative tool, which keeps it just short of a 5.

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