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

No annotations are present, so the description carries the full burden of behavioral disclosure. It communicates that the operation is a mutation and that a supported plan is needed, but it does not disclose uniqueness constraints, whether the old alias becomes available, timing, idempotency, or what the response indicates about success.

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 a single, focused sentence with no redundant phrasing. The core action and resource are front-loaded, and the plan requirement is appended without adding clutter.

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 two-parameter mutation tool with a fully documented schema, the description covers the essential operation and plan requirement. However, with no annotations and no output schema, it leaves gaps around expected behaviors such as alias conflict handling, whether the destination remains unchanged, and failure conditions.

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 schema already documents both parameters. The description adds minimal semantic value beyond matching 'surl' to 'existing short link' and 'new_alias' to 'custom alias', but it does not provide extra format, uniqueness, or validation details.

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 states a specific action ('Update'), a specific resource ('custom alias of an existing short link'), and a plan prerequisite. This clearly differentiates it from the sibling update_destination, which would update the destination URL rather than the alias.

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 prerequisite ('requires supported plan') but does not explicitly say when to use this tool versus alternatives such as update_destination or create_short_link. Usage context is implied rather than directly stated.

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