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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the mutation risk is known. The description does add real value beyond them by disclosing the concrete consequence: the profile URL changes and the profile is automatically migrated. It stops short of the questions a destructive operation raises – what happens to existing shortlinks pointing at the old alias, whether the old alias is released, and whether the change is reversible.

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?

Three short sentences, front-loaded with the action and immediately followed by the observable effect. Nothing is padding, though the migration sentence could be folded into the URL sentence without loss.

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-parameter mutation with annotations present and no output schema, this covers the essentials: what changes and the resulting URL. The remaining gap is the destructive side effects on existing links and alias availability, which matters given destructiveHint=true.

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 single 'alias' parameter is already documented in the schema as the new alias to switch to. The description reinforces this with the URL format example, but adds no constraint details such as allowed characters, length, or uniqueness requirements. 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 names a specific verb and resource ('Change the user's alias/username') and quantifies the effect ('from urlinks.me/{old} to urlinks.me/{new}'). It is clearly distinguishable from get_alias, but it never mentions create_alias, so the create-vs-update boundary is left implicit.

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?

Usage is only implied by the word 'Change' – it must be used on an existing alias rather than a new one, but that is never stated and no alternative (create_alias) is named. There is no guidance on prerequisites, existing-link handling, or when this is the wrong tool.

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