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

Goes well beyond the annotations by disclosing a concrete rate limit ('3 codes, at least a minute apart') and a delivery-scope constraint (only the application's number). This is exactly the kind of side-effect context the annotations (openWorldHint=true, idempotentHint=false) cannot express on their own.

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?

Three sentences, front-loaded with the primary action, then the follow-up step, then the constraint. No filler or restatement of the tool name.

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?

Complete for a 2-param tool with full schema coverage and no output schema: purpose, next step, and rate limit are all covered. It stops short of explaining behavior at the 3-code limit or failure modes, a minor omission.

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 both parameters are already documented in the schema and the description adds no parameter-level syntax or format detail. 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?

States a specific verb ('Texts') and specific resource ('6-digit code') with an explicit destination constraint ('the mobile number in the application, never any other number'). An agent can distinguish this from sibling send_phone_code/confirm_phone_code flows via the named follow-up step partner_confirm_code.

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?

Gives clear sequencing guidance ('Ask the person to read it to you, then call partner_confirm_code'), which routes the agent to the correct next tool. It does not, however, state when NOT to use this versus the sibling send_phone_code, so the when-not case 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.