render_template

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

There are no annotations, so the description carries the full burden. It discloses auth requirements and the fact that it returns rendered content, which is useful. However, it does not state whether any side effects occur or explicitly confirm that no message is sent.

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 brief and front-loaded with the core purpose and return value. The ACCESS note adds relevant operational context without excessive fluff, though 'start_login does NOT open this tool' is a slightly odd aside.

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 simple render operation, the description is mostly adequate and includes critical access details. The main gap is that it does not explain how message_type selects a template or how variables map to template placeholders, which could leave an agent uncertain in a large sibling tool set.

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. The tool description adds no parameter-level meaning beyond what the schema already provides. The message_type field remains vague in both the schema and the description.

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 verb and resource: 'Render a template with provided variables' and identifies the return value as 'fully rendered message content.' It is specific enough to understand the tool, though it does not explicitly distinguish itself from the sibling preview_template.

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 access context: a Proof account is required, PROOF_API_KEY must be set, and the server must be restarted. It also warns that start_login does not open this tool. It lacks explicit comparison to alternatives like preview_template, but the prerequisites are unusually helpful.

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