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

Adds real context beyond the annotations (readOnly=false, destructive=false): it discloses the return value ('running total of the job'), the customer-visible side effect boundary ('Nothing reaches the customer until you send the estimate or invoice'), and the auth requirement (Cotlet API key with app access). This is meaningful behavioral disclosure for a mutation tool.

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 and scope are front-loaded in the first sentence, followed by batching, side-effect scope, and auth in a logical order. Five sentences all carry information, though the auth sentence has a slightly boilerplate feel.

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-line mutation with full schema coverage and annotations present, the description covers purpose, invocation pattern, side-effect boundary, and return value ('running total'). The absence of an output schema is compensated by the stated return. Minor gaps (no mention of what happens if the line already exists) keep it from 5.

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 all six parameters are already documented in the input schema (item, job_number, quantity, price_per_unit, taxable, description). The description adds no syntax, format, or defaulting detail beyond the schema, so the baseline of 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 ('Add one charge item') plus its scope ('to the estimate or invoice of a job or opportunity'), which distinguishes it from siblings like kickserv_generate_invoice and kickserv_send_invoice. An agent can identify exactly what entity this mutates without opening the 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?

Gives clear calling guidance: 'Call it once per line' encodes the batching pattern, and 'it runs without asking first' clarifies the confirmation policy for this mutation. It does not name alternative tools or explicitly state when-not-to-use, so it falls short of the 5 mark.

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