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

Beyond the annotations, the description discloses substantial behavior: no credential required, data stays in the workspace, no charge until the owner confirms the letter, one workspace per domain, throwaway mail domains refused, and what the returned API key represents. The two-phase lifecycle (owner confirms then signs in, agent acts as them) is exactly the kind of context annotations cannot express, and nothing contradicts readOnlyHint=false or idempotentHint=false.

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 action is front-loaded in the first sentence and most subsequent sentences carry real constraints. A few sentences are dense and awkwardly constructed ('The API key answered here, once, is for an agent with no person behind it'), which slightly slows parsing, but there is little pure filler.

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 five-parameter creation tool with annotations but no output schema, the description covers prerequisites, refusal conditions, billing, and the post-creation handoff to the owner. It leaves the response payload unstated, which is a modest gap given no output schema exists to carry that information.

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 five parameters, including the 'tommo' enum and its trial semantics. The description adds contextual meaning (owner must be human, on the company's own domain; agent_name becomes the key's name) but no syntax or format detail beyond the schema, so the baseline of 3 applies.

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 opening sentence gives a specific verb and resource ('Open a Tommos workspace for a company, with a human owner'), so an agent immediately knows what is produced and for whom. It implicitly separates the human-owner path from the credentialless/agent-only path, but never names a sibling tool for contrast, so it stops short of full differentiation.

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 implied rather than stated: the prerequisites ('One workspace per company domain; a public or throwaway mail domain is refused') and 'Needs no credential' tell the agent when the call will succeed or be rejected. There is no explicit 'use this instead of X' routing against any of the many sibling tools, so guidance remains inferential.

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