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

With no annotations, the description carries the full disclosure burden. It does well by stating the side effect that the tool 'Replaces the default template' and by disclosing the access requirement and the start_login caveat. It does not mention response behavior, reversibility, or conditional effects like whether email-only parameters apply, but the core behavioral trait of overwriting the default template is explicitly surfaced.

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 compact and front-loaded: the main purpose is stated in the first sentence, the key side effect in the second, and the access requirement plus the important start_login caveat in the final block. Every sentence earns its place, and the structure makes the most critical information immediately visible.

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?

The description is solid for a mutation tool with full schema coverage, but there is no output schema and no mention of what the tool returns or confirms after success. It also does not explain what happens if a template already exists beyond the 'Create or update' phrasing. Given the lack of return-value documentation, a 3 reflects that it is adequate but not fully 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 baseline is 3 even without additional parameter details in the description. The description adds only general context about 'specific channel and message type,' which is already reflected in the schema. It does not clarify non-obvious semantics like placeholder syntax or conditional subject/button requirements beyond what the schema already provides.

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 identifies the verb and resource: 'Create or update a custom template for a specific channel and message type.' It also adds the meaningful detail that it 'Replaces the default template,' which distinguishes its effect. However, it does not explicitly distinguish this from sibling template tools like update_profile_template or preview_template, so it stops short of a 5.

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 gives clear operational context: a Proof account is required, the client must be authenticated before retrying, and it explicitly warns that 'start_login does NOT open this tool.' This gives the agent a concrete when-and-how-to-use signal. It does not name alternative tools for template editing or previewing, so it lacks the full 'when-not/alternatives' detail needed for a 5.

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