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

Goes beyond annotations by disclosing the mutation effect ('the invoice's remaining amount and status change'), the confirmation behavior, and the auth requirement (Cotlet API key with app access). Annotations already flag mutation and open-world reach, but the description usefully specifies what actually changes.

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?

Purpose is front-loaded, but the opening two sentences restate the same idea ('Link a bank transaction... Matches a bank transaction...'), and the confirmation guidance is spread across several sentences with some redundancy.

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 mutation tool with no output schema, the description covers side effects, confirmation expectations, and auth needs — enough for an agent to call it safely. The main gap is the absence of any note on the result of a successful match.

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 coverage is 100%, and the schema already documents both IDs and where to source them (list_customer_invoices/create_customer_invoice, list_transactions). The description adds only the incidental 'check the amount first' note, so baseline 3 is appropriate.

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: 'Link a bank transaction to a customer invoice as its payment.' The purpose is unambiguous and clearly distinct from sibling read tools like pennylane_list_transactions and pennylane_categorise_transaction.

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?

Explains the scenario it applies to — 'payments made outside it, such as a bank transfer' — which tells the agent when to reach for it. It stops short of naming an explicit alternative or a when-not-to-use condition, so it is clear context rather than full routing guidance.

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