dns_set_cname

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

Goes well beyond the annotations (readOnlyHint=false, destructiveHint=true). It discloses that records are safely merged, that setting a CNAME makes the zone set_type exclusive and breaks A/MX/TXT, and that force is needed when CAA/SRV exist — exactly the destructive side effects an agent must know before calling.

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?

Front-loads purpose, then the critical warning, then Args — a sensible ordering. The prose is dense and non-redundant, though the Args block is somewhat verbose relative to a 4-parameter tool.

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 mutation tool with an output schema present, the description supplies everything needed: purpose, exclusivity warning, merge behavior, and per-parameter meaning including the force precondition. Return values are correctly left to the output schema.

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 coverage is 0%, so the Args block carries the full burden and documents all four parameters: fqdn (subdomain form), cname (trailing-dot handling), ttl (delegated to dns_set_a), and force (CAA/SRV continuation). TTL being deflected to another tool leaves one semantic partially unstated, preventing a 5.

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 ('Задать CNAME-запись для поддомена'), which unambiguously separates it from the sibling record-setters (dns_set_a, dns_set_txt, dns_set_mx, dns_patch_record) by record type. An agent can select it without opening any 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?

Gives explicit when-not guidance: 'Используйте CNAME только на поддоменах, где у вас нет других записей', plus the exclusivity caveat that A/MX/TXT stop working. It references dns_set_a for TTL semantics, but does not name an alternative tool or fallback path if the subdomain already has records.

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