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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower; the description adds genuine value by disclosing the shape of the response (field list) for a tool that has no output schema. It does not mention pagination or total-count behavior beyond what the parameter schema already states.

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?

Two tight sentences plus an endpoint path — the resource and returned fields are front-loaded with no padding. The raw 'GET /api/v2/taxes' path is mildly redundant for an agent that only invokes the tool, but it costs almost nothing.

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 list tool with one well-documented optional parameter, the description covers the resource, the returned fields (compensating for the absent output schema), and the key relational fact of what TaxId means. Nothing needed to call it correctly is 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% and the single max_results parameter is fully documented in the schema, including the default of 100, the max of 1000, and the total-count reply semantics. The description adds nothing about it, so the baseline of 3 applies.

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 resource (all VAT rates of the company) and enumerates the exact fields returned (TaxId, code, name, percent, active flag), which no other sibling list tool covers. An agent can tell this apart from merit_list_items, merit_list_accounts, etc. 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?

Usage is only implied — the description notes 'The TaxId is what invoice rows refer to,' which hints at when an agent needs this data (resolving invoice-line tax references), but it never says when to call this versus other list tools or whether any prerequisites exist. Adequate context, no explicit when/when-not guidance.

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