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

Goes well beyond the annotations: it discloses that payment reminders follow the plan afterwards, that a missing message falls back to the default template, that calls are confirmed by default and can be toggled off, and that it requires a Cotlet API key with app access. The 'reaches other people' confirmation warning is valuable external-effect context, though somewhat procedural and repetitive.

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?

Front-loaded with the core purpose, but the first two sentences are near-duplicates ('with a link to it' / 'with the invoice link'), wasting space. The remaining sentences earn their place but the redundancy costs a point.

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 two-parameter mutation tool with annotations covering the safety profile and no output schema, the description supplies the key missing context: side effects (payment reminders), auth requirement, and confirmation/outreach behavior. Only the lack of explicit alternative-routing and return feedback keeps it from a 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 coverage is 100%, so both parameters are already documented. The description only adds the default behavior for the message parameter (falls back to the email template); it adds nothing for invoice_id beyond what the schema already states.

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 (email) and resource (invoice) plus the recipient (client) and mechanism (link). It is clearly distinguishable from dubsado_create_invoice and dubsado_record_manual_payment, but it never names an alternative sibling, so it stops short of the 5 bar.

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 only implied: the tool assumes an invoice already exists and is being delivered to a client. There is no explicit when-to-use versus alternatives (e.g. create_invoice, record_manual_payment) and no exclusion conditions beyond the generic confirmation note.

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