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

With no annotations, the description must carry the full behavioral burden. It usefully discloses preconditions (different accounts, opposite transaction types) and which side each ID represents, but it does not say whether the link is reversible, what happens to balances, what permissions are needed, or what the result of a successful link is. Some behavior is added beyond the schema, but key mutation details are missing.

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 tightly written sentences with zero waste. The core action is front-loaded, followed by the key constraints and parameter roles.

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 simple two-parameter mutation with no annotations and no output schema, the description covers what the agent needs to invoke it correctly — required parameters, their roles, and preconditions. However, it omits reversibility and side-effect information that would help an agent reason about the mutation, so it is adequate rather than 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 100%, so the baseline is 3. The description reinforces the roles of baseTxId and oppositeTxId and adds the account/type relationship constraint, but it does not add syntax or format meaning beyond what the schema already provides.

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 gives a specific verb ('Link') and resource ('two existing transactions as a transfer pair'), and the 'transfer pair' framing is distinctive enough to separate it from adjacent linking tools like link_refund or link_transaction_to_portfolio. It stops short of explicitly naming a sibling to avoid or a condition that selects it, so it is clear but not fully differentiated.

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 states prerequisites — different accounts and opposite types — which implies when the tool applies, but there is no explicit guidance on when to choose this over unlink_transfer or other linking tools. The usage context is therefore inferred rather than spelled out.

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