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

Annotations only include readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false, so the description carries the burden. It discloses that an email is sent with a confirm link and six-digit code, that a request_id is returned, that the account is created on first confirmation, and that nothing is charged. This is transparent, though it does not mention failure modes or what happens if the email is not confirmed.

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 description is concise enough and front-loaded with the purpose. It is structured logically: purpose, parameters, behavior, next step. Each sentence adds value, though the instruction to tell the user and then call verify could be slightly more compact, it is clear and not overly verbose.

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-step authentication tool with two parameters and no output schema, the description covers the essential information: purpose, parameters, the email behavior, the return of request_id, the need to call verify, and the no-charge/no-card aspect. It lacks details on error handling or the exact structure of request_id, but that is not critical for invocation.

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 0%, so the description must explain parameters. It mentions 'email' and 'language' and explains the language is the language spoken with the user, with examples ('lt', 'en', 'de'). It clarifies that language is optional via the default, and that email is sent in that language. This adds meaning beyond the schema's bare property definitions.

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 description clearly states the tool's purpose: 'Sign in, inside the chat (needed to enable services and call their tools).' It explicitly identifies it as step 1 of 2 and differentiates it from the sibling datailo_connect_verify by describing the subsequent call. The verb 'sign in' and the resource 'Datailo' are specific, and the scope is unambiguous.

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?

The description provides clear context for when to use this tool: 'needed to enable services and call their tools.' It also instructs the agent to tell the user to click the confirm link and then immediately call datailo_connect_verify(request_id), which defines the flow. It does not explicitly state alternatives (since there are none for sign-in), but the guidance is sufficient.

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