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

Annotations already declare destructive=true, non-idempotent, and openWorld, so the write semantics are covered structurally. The description adds real operational context beyond them: the web server is reloaded as a side effect, and the domain's DNS must already point at the server before issuing. It stops short of noting Let's Encrypt rate limits or re-issue behavior on an existing certificate, which are the main remaining operational risks.

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?

Opens with a WRITE marker, then mode selection, then side effects and prerequisites, then the exclusion, then the endpoint paths. Three dense sentences with no filler; the highest-value routing information is front-loaded.

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 an 8-parameter, 5-required mutation with no output schema and full schema coverage, the description supplies the mode logic, preconditions, and side effects an agent needs to call it correctly. It omits what a caller should expect on failure (e.g., DNS validation failure or rate limiting), which is the only notable gap.

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 every parameter including the enums and the dns-01/external_api coupling is already documented in the schema. The description restates the domain_id/advanced-mode relationship but adds no format, syntax, or default detail the schema lacks, so the baseline 3 applies.

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 and resource ('issue and install a free Let's Encrypt certificate') and immediately splits the two operating modes (basic webapp SSL vs advanced per-domain SSL). It also distinguishes itself from sibling runcloud_get_ssl_method, which it names as a prerequisite lookup rather than a duplicate.

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?

Explicit routing rules: basic SSL for the whole web application, advanced SSL for one domain via domain_id, and the constraint that advanced mode must already be configured (pointing to runcloud_get_ssl_method). It also names a negative case — custom certificates are not supported here — which steers the agent away from misusing this tool.

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