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

Annotations already declare non-read-only, open-world, non-idempotent, non-destructive behavior, so the safety profile is partly covered. The description adds regulatory context ('SwapEazi does not hold or move money') and the quote-feed attachment behavior, which is useful, but it never warns that retrying may create duplicate enrollments despite idempotentHint=false, nor what the caller gets back.

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?

It is short and front-loads the actor list, but the sentence fragments and the stray 'Keyed.' opener cost clarity without earning space. The disclaimer sentence is better placed after the operational facts.

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 9-parameter, 3-required enrollment mutation with no output schema, the description covers who joins and how rails attach feeds, but says nothing about what a successful call returns (an access key? an enrollment status?) or what happens to an existing party that re-joins. That leaves a real gap for an agent invoking it blind.

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 all nine parameters including party, rail_kind, from/to, and rate are already documented in the schema. The description reinforces that a rail attaches exactly one published rate and an optional api_key or oauth quote feed, but adds no syntax or format meaning beyond the schema, so 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?

The description conveys that a party (business, rail, or agent) joins the network and that rails can attach a quote feed plus one published rate. But the opening fragment 'Keyed.' is opaque, and it never distinguishes this enrollment action from the closely related sibling connect_rail_account, so an agent can't confidently pick between them from the text alone.

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 explicit when-to-use or when-not-to-use guidance, and no alternative is named even though connect_rail_account and request_introduction sit in the same sibling set. The 'No placement is sold' line hints at scope but is framed as a disclaimer, not as usage direction.

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