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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered and the description is consistent with it. The description adds that the result is a publishable TXT record and where it belongs, but says nothing about the keyType default or whether the output is a single string, so it adds only modest behavioral context.

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?

A single front-loaded sentence with no filler; the operation and its output destination are stated compactly and nothing is wasted.

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?

With no output schema, the description usefully states what the return value is (a formatted TXT record), which covers the main richness gap. It still omits the keyType default and any note about the required public key format beyond the schema, so it is nearly 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 only 33%: only publicKey is documented, while selector and keyType are bare (keyType has an enum but no default). The description recovers the selector's meaning by placing it into the DNS hostname, but leaves keyType (rsa vs ed25519) and its default unexplained, so it only partially compensates for the coverage gap.

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 names a specific verb (format) and resource (DKIM public key as a TXT record), so the transformation is unambiguous. It does not explicitly distinguish itself from the sibling check_dkim or from generate_spf_record/generate_dmarc_record, 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?

There is no statement of when to use this tool versus check_dkim, nor any precondition such as 'use after generating a keypair.' The record location hint ('publish at selector._domainkey.yourdomain') only faintly implies a setup context, which is not enough to count as guidance.

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