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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds that the response includes splits and tag ids, which is useful behavioral context beyond the schema. However, it does not disclose other behaviors like whether the transaction is returned with all fields, or any error conditions (e.g., not found). With annotations covering safety, a 3 is appropriate.

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?

A single sentence that is front-loaded with the action and resource, and includes the key detail about splits and tag ids. No wasted words.

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 tool with annotations covering safety and a schema covering parameters, the description is complete enough. The only minor gap is that it doesn't mention what happens if the transaction is not found, but that is not critical for an agent to invoke the tool 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 schema already documents both parameters. The description adds that transactionId is a ULID and that the result includes splits and tag ids, but it doesn't add meaning beyond the schema's parameter descriptions. Baseline 3 is correct when schema does the heavy lifting.

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 states a specific verb ('Fetch'), a specific resource ('a single transaction'), and the key identifier ('by its ULID'). It also mentions the inclusion of splits and tag ids, which distinguishes it from a generic get_transaction. Among siblings like get_account, get_budget, get_payee, this clearly identifies its target resource.

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?

The description implies the tool is for fetching a single transaction, which is clear context. It does not explicitly state when not to use it or name alternatives like list_transactions for multiple transactions, but the singular 'a single transaction' provides enough guidance for an agent to select it appropriately.

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