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

Annotations already indicate this is a non-read-only, non-destructive mutation. The description adds valuable behavioral context by stating that only a single link is added and that the allocation's other links are preserved, distinguishing it from a replace-all operation. It does not mention edge cases like duplicate links or error behavior, but given the annotation coverage, this is sufficient.

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 two sentences long and front-loads the core purpose. The second sentence earns its place by clarifying the behavioral distinction from an alternative tool, with no redundant or filler content.

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 simple two-parameter mutation tool with annotations and full schema coverage, the description is complete. It covers the action, the cross-resource relationship, the required same-project constraint, and how it differs from the closest alternative. No output schema exists, but the description does not need to explain return values for this level of complexity.

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 input schema already provides descriptions for both task_id and allocation_id, including the same-project constraint, so schema coverage is 100%. The description's narrative adds little beyond what the schema states; it reinforces the relationship but does not introduce new parameter-level 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 clearly states the tool's function with a specific verb and resource: 'Link one task to an allocation.' It also explains the underlying purpose ('showing what task work sits behind the committed time') and distinguishes itself from twprojects-update_allocation by contrasting additive linking with replacing the whole set.

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 provides clear context: the task and allocation must be in the same project, and this tool adds a single link rather than replacing existing links. It explicitly names the alternative twprojects-update_allocation and explains the key difference, though it does not enumerate broader when-not-to-use scenarios.

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