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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=true), so the bar is lower. The description goes beyond them by disclosing an auth prerequisite (the user's Cotlet API key with access to this app) and the fact that results come back in SnelStart's own ordering; it omits pagination/rate-limit behavior.

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 and readable, but redundant: the VAT number and email address are stated twice ('with name, VAT number and email address' then 'with the VAT number and the email address on the card'). The email/invoicing aside is useful context but the middle sentence largely restates the first.

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?

With no output schema, the description usefully names the returned fields and explains ordering, and it covers the auth requirement. All three parameters are documented in the schema, so the remaining gap (pagination behaviour around cursor/limit) is minor for a read-only list tool.

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 limit, query and cursor are already self-documented and the baseline is 3. The description adds no parameter-level detail (no filter syntax or paging guidance), and its VAT/email mentions refer to returned fields, not inputs.

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 (lists customers) and even gives the SnelStart-native names ('Relaties, Klanten') plus the fields surfaced (name, VAT number, email). An agent can tell this apart from snelstart_create_customer or snelstart_get_sales_invoice, though it does not explicitly contrast itself with any sibling.

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?

There is no explicit when-to-use/when-not-to-use statement or named alternative. Usage is only implied, e.g. the note that SnelStart Web only mails invoices to a filled-in email address hints at why an agent would pull this list, but the routing logic is left to inference.

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