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

Annotations already declare readOnlyHint and idempotentHint true, covering safety. The description adds that the list is an allow-list specific to the user and includes per-user aliases, which is useful context beyond the annotations. The warning about not inventing ids further clarifies expected behavior. No contradiction.

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?

The description is exceptionally concise: two sentences that front-load the purpose and then add a critical usage warning. Every word earns its place, with no fluff or repetition.

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 zero-parameter tool with an output schema, the description covers all necessary context: the scope (OAuth user), the nature (allow-list with per-user aliases), and the critical constraint (never invent ids). An agent has everything needed to invoke and interpret the tool correctly.

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?

The tool has zero parameters, so the baseline for parameter semantics is 4. The description doesn't need to document parameters, and it doesn't, but it does not hinder understanding. The schema is empty, so there is nothing to add.

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 clearly states this tool lists the allow-list of destinations for the OAuth user, with per-user aliases. It is distinct from any sibling tool (no other destinations-related tool exists), so the purpose is unambiguous and actionable.

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 description includes a critical usage directive: 'Never invent ids,' which tells the agent to only use returned ids and not fabricate them. It also scopes the list to 'this OAuth user.' However, it does not explicitly contrast with alternatives, but given no sibling does destinations, this is sufficient.

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