Update qURL Token

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

Annotations already flag this as a mutating, non-idempotent, non-destructive operation, so the description adds value by disclosing key invariants: `extend_by` and `expires_at` are mutually exclusive, at least one token update field must be set, and the operation returns the updated token summary. This goes beyond what annotations alone provide, though details like access-policy replacement semantics are only implied and left to the schema.

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 compact and front-loaded: it opens with the action and scope, then provides routing guidance, then lists constraints in a clearly labeled block. Every sentence earns its place, and the structure makes it easy for an agent to scan and act on.

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?

With eight parameters, nested access-policy objects, and a rich sibling set, the description covers the core invocation context—what to update, when to use it, which siblings to prefer, and key constraints. The output schema relieves it from detailing return values. It could have explicitly stated that `access_policy` replaces the entire policy, but the schema's field description already communicates this.

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 adds meaningful semantic constraints not derivable from the schema's `required` array alone—that at least one token-update field must be supplied and that `extend_by` and `expires_at` cannot be combined. It also groups the updateable fields, helping an agent understand the intent of the parameter set.

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?

Description states a precise action—'Update one qURL token under a resource'—and enumerates the mutable fields: expiration, label, access policy, max sessions, or session duration. It explicitly differentiates from siblings by contrasting with `update_qurl` and `revoke_qurl_token`, making the tool's scope unambiguous.

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?

Provides a direct when-to-use condition: 'Use this when you need to change a specific `q_…` token without changing sibling tokens or resource-level metadata.' It also names alternatives and the exact conditions that select them: use `update_qurl` for resource-level changes, and `revoke_qurl_token` when the token should stop working entirely.

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