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

Annotations only cover the generic write profile (readOnlyHint=false, destructiveHint=false, idempotentHint=false), and the description adds substantial non-obvious behavior: the caller becomes owner, a unique slug is auto-generated, the current session product is NOT switched, DNS/DKIM/SPF/DMARC authentication is needed post-creation, and a conflict error is returned on duplicate name or domain. This is well beyond what the annotations convey.

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 required inputs are front-loaded, and nearly every sentence carries operational information (ownership, slug, session behavior, DNS prerequisite, error case, return payload). It is long, and the two consecutive 'Returns...' sentences could be merged, but there is little genuine padding.

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?

Even with no output schema, the description states the return payload (id, name, slug, domain, from_email, next steps) and the error case, and it covers the post-create DNS/provider workflow the agent must communicate. For a multi-parameter mutation tool this is unusually complete.

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 the schema already documents all 8 parameters including defaults for from_email and primary_color. The description only restates the two required inputs (name, sending domain) and the example domain; it does not add syntax or format meaning beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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?

Opens with a specific verb+resource ('Create a brand-new Meisa product') and immediately defines what a product is (app or brand with its own sending domain, contacts, sequences, templates, broadcasts). It distinguishes itself from working inside an existing product and from meisa_switch_product, so an agent can place it among the many sibling create_* tools without opening a 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?

Explicit when-to-use: 'when the user wants to add another product or brand to their Meisa account, rather than working inside an existing one.' It also names the required follow-up (call meisa_switch_product afterwards to make it active) and the exception (unless it is the user's first product), which is exactly the routing guidance an agent needs.

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