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

Annotations already declare readOnly, idempotent, non-destructive and open-world behavior, so the bar is lower. The description still adds output-shaping context by saying it returns ALL live records (i.e., unfiltered), which the annotations do not convey.

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?

Two sentences, zero waste, with the usage trigger front-loaded before the return behavior. Nothing needs trimming, though there is little beyond the minimum.

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 bears some responsibility for describing what comes back, and it only says 'all live TXT records' without indicating record format, count, or failure behavior (e.g., NXDOMAIN). Adequate for a one-parameter lookup, but thin given the absent 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 100% for the single domain_name parameter, and the description adds no format, validation, or example detail beyond the schema's own 'e.g. example.com'. Baseline 3 is appropriate when the schema carries the full parameter burden.

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 and resource ('see a domain's TXT records') and scopes the result set ('all live TXT records'). It does not, however, explicitly distinguish itself from the similarly generic sibling dns_lookup or from the policy-specific spf_check/dmarc_check tools.

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?

It gives an explicit use context ('when the user wants to see a domain's TXT records') plus concrete motivating examples such as verification tokens. It stops short of stating when NOT to use it, even though siblings like spf_check and dmarc_check overlap with one of the cited examples (checking SPF policies).

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