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

The readOnlyHint annotation already establishes this as a safe read. The description adds real value by disclosing return contents (rows with ledger, VAT code, amount, relation, invoice number) in the absence of an output schema. It says nothing about not-found behavior, auth, or pagination.

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 with the resource and its row contents front-loaded. The raw endpoint reference is mildly redundant but not wasteful.

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 single-parameter read tool with no output schema, listing the returned row fields largely closes the gap that the missing output schema would otherwise leave. The only real omission is routing guidance versus the list_mutations sibling.

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 id parameter is fully documented in the schema, including its source. The description adds no format or semantics beyond that, so the baseline 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 ('One mutation with its rows') and enumerates the row contents, which lets an agent distinguish it from the plural list tool. The verb is only implied via the title, but the singular scope is clear.

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 implied: fetch a single booking by id, with the schema hinting the id comes from eboekhouden_list_mutations. The description itself never names the list sibling or states when to prefer one over the other, so the agent must infer the get-by-id vs list distinction.

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