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

Annotations only give readOnly=false, openWorld=true, destructive=false. The description adds real behavioral context beyond them: it returns the new balance due, the confirmation default, and that it requires the user's Cotlet API key with app access. This is genuinely additive.

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?

The core purpose is front-loaded, but the first two sentences are near-duplicates ('Record a full or partial client payment on an invoice' repeated) and the trailing auth/confirmation boilerplate is generic. It is not bloated, but it wastes the opening sentence.

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 4-param mutation tool with no output schema, the description covers the essentials: what it mutates, that it returns the new balance due, the confirmation requirement, and the auth prerequisite. Only the when-to-use dimension is thin.

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%, so the schema already documents all four parameters. The one description detail ('The memo holds a check number or note') merely restates the schema's own memo description, adding no new meaning. 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?

The description states a specific verb and resource ('Record a full or partial client payment on an invoice') and even notes the return value. It does not, however, differentiate itself from the many other *_record_payment siblings, though the 'Knowify:' prefix anchors the app.

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?

It provides a confirmation policy ('By default you confirm each call; you can switch that off for this tool') and a caution to confirm before each call, which is useful context. But it never says when to prefer this over alternatives such as listing invoices or sending an invoice, so usage selection is only implied.

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