Get Tax Facts

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the useful behavior that it returns both the figure and its source, but it does not disclose data currency, per-category behavior, or what happens when a requested figure is unavailable.

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?

One focused sentence front-loads the action and resource, then gives a compact category enumeration, then states the return behavior. Every part earns its place and nothing repeats the structured schema.

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 simple read-only lookup with full schema coverage, safety annotations, and no output schema, the description is complete: it states what to look up, which categories are supported, and what the response contains. No additional return-format, pagination, or invocation details are needed for an agent to use 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 baseline is 3; the schema already explains category, item, and tax_year defaults. The category list in the description is illustrative but adds no real meaning beyond what the schema examples and item description already convey.

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 names a specific verb ('look up'), a clear resource ('current UK tax rates, thresholds and allowances'), and enumerates supported categories, so an agent knows what the tool returns. It does not explicitly differentiate itself from sibling tools like search_tax_facts or lookup_tax_rule, which keeps it from a 5.

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?

There is no guidance on when to use this tool versus alternatives such as search_tax_facts, get_vat_summary, lookup_tax_rule, or get_gov_guidance. The description gives context ('current' rates) but no exclusions, prerequisites, or routing conditions.

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