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

Annotations declare this is a non-read-only, non-destructive, non-idempotent, closed-world mutation. The description adds two things annotations cannot: the rejection is externally visible in the counterparty's log, and an organization API key is required. It stops short of saying what happens to the local handshake state or what a repeat call does, which matters given idempotentHint=false.

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, both front-loaded with the action and then the key constraint and auth requirement. Every clause carries information an agent needs; nothing is padding.

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 one-required-param mutation with no output schema and a full set of annotations, the description covers scope, side effect visibility, and auth. The remaining gap is what the caller gets back and how the handshake's state changes, which is minor given annotations already signal the safety profile.

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%, so both parameters (handshake_id format 'hs_...', and the shared reason) are already documented in the schema. The description adds no parameter-level detail beyond that, so the baseline of 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?

States a specific verb (reject) and resource (handshake addressed to your organization), and adds the consequence that the other company's log records the rejection. It is clearly distinguishable in intent from the sibling ledger_handshake_accept, though it never names that sibling to sharpen the contrast.

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?

The phrase 'addressed to your organization' scopes which handshakes this applies to, which implies usage. But there is no explicit when-to-use versus when-to-accept guidance and no mention of the sibling ledger_handshake_accept as the alternative path.

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