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

Annotations only declare safety flags (readOnlyHint=false, destructiveHint=false, openWorldHint=false). The description adds genuinely non-obvious behavior: the single-active-sprint invariant across every plan, the failure mode, and the fact that the error names the blocking sprint — none of which is derivable from the schema or annotations.

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?

Two sentences, front-loaded with the use condition followed by the constraint and recovery path. Every clause carries information; no restatement of the title or schema.

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 minimal one-parameter mutation with safety annotations and no output schema, the description covers when to call it, the invariant, and the failure/recovery path. The only meaningful hole is not identifying what `id` refers to.

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 0% for the single required `id` parameter. The description implies the id identifies the previously planned sprint but never states what identifier is expected (sprint UUID vs. name), so it only partially compensates for the schema gap; the UUID pattern constrains the type but not which entity.

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?

States a specific verb and resource (begin a previously planned sprint) and makes clear it operates on an existing sprint rather than creating one, distinguishing it from create_sprint. It does not explicitly name the sibling that creates sprints, so an agent must infer the boundary from 'previously planned'.

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?

Gives an explicit trigger condition ('when the user is ready to begin a previously planned sprint'), the precondition that only one sprint can be active per plan, the failure behavior, and the concrete remedy (complete_sprint, then retry). Nothing about when/when-not is left to inference.

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