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

Annotations establish the write/non-destructive/non-idempotent profile, so the bar is lower, and the description adds real value on top: a per-plan quota (Free 3) and the fact that exceeding it returns a tool error rather than silently succeeding. It also discloses that the response carries an id. Auth requirements and whether re-creating the same name collides are not covered.

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 short sentences, all load-bearing: what it does and returns, the quota boundary, then the downstream render path. The most actionable fact (id is returned) is front-loaded and nothing is repeated from the schema.

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 6-parameter write tool with nested page_options and no output schema, the description covers the outcome (returns an id), the failure boundary (plan cap), and the follow-on workflow, which is what an agent needs to sequence calls. Remaining gaps, such as permission requirements and name-collision behavior, are minor rather than blocking.

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%, with css, engine, content format, sample_data, and page_options all documented in the schema, so the baseline of 3 applies. The description only gestures at data via "template_id plus data" and adds no syntax or constraint detail beyond what the schema already states.

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?

Specific verb+resource ("Save a new reusable template") with the concrete side effect of returning an id. The word "new" plus the account-level scope clearly separates it from update_template, get_template, and list_templates in the sibling set. An agent can select this tool without opening the schema.

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?

States the creation context and the natural follow-on path ("Render it later with render_pdf or render_image and template_id plus data"), which is genuine routing guidance toward siblings. It does not state when to use update_template instead or any prerequisites such as required permissions, so it stops short of explicit when-not guidance.

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