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

With no annotations present, the description carries the full behavioral burden, and it delivers the most important trait: the tool refuses with a do_not_answer signal when data is drifted or unverified and never guesses. That failure-mode disclosure is genuinely valuable. It still omits what a success response contains and what happens for an unknown fact_id.

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 short sentences, zero filler, and the core behavior (retrieve one fact) is front-loaded ahead of the refusal caveat. Nothing is redundant with the title or 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?

With no output schema and no annotations, the description has to cover purpose and behavior, which it partly does. It leaves two real gaps for a single-parameter lookup: how to obtain a valid fact_id and what the returned fact looks like.

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 0% and the single parameter fact_id is never explained in the description — no format, no provenance, no note that it comes from the corresponding list_facts tool. The name is somewhat self-explanatory, but the description adds nothing beyond it.

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 ('Get one verified fact') and scopes it to the ferryuk pack, which separates it from the sibling list/changes tools by cardinality ('one' vs a list). It does not explicitly name ferryuk_list_facts as the alternative, so the differentiation is implied rather than stated.

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?

Usage is only implied: an agent can infer this is the single-fact lookup once it has an identifier, but the description never says to call ferryuk_list_facts first to obtain a fact_id, nor when to prefer ferryuk_changes for freshness. No explicit when/when-not guidance.

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