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

Annotations already declare destructiveHint=true, idempotentHint=false, and readOnlyHint=false, so the agent knows this mutates state; the description usefully adds partial-update semantics for the omitted-field case. It does not disclose the consequences flagged by destructiveHint — e.g., whether an existing note is overwritten rather than appended, or whether changing stage discards prior stage history.

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 followed by the partial-update rule and the enum. The enum list is somewhat redundant with the schema, but it is compact and does not bloat the definition.

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 three-parameter mutation tool with no output schema, the description covers the action, the optionality of fields, and the stage vocabulary. It leaves open what the call returns and whether a tracking record must pre-exist, which are the main remaining gaps for an agent invoking it unsupervised.

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 coverage is 100%, so all three parameters are already documented and the stage enum is fully enumerated in the schema; restating the valid stages in the description adds little beyond that. The one genuine addition is the omit-to-leave-unchanged rule, which clarifies that both mutations are optional and independent.

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 verb and resource ('Set the application stage and/or a free-text note') and scopes it to 'a vacancy the user is tracking,' which separates it from generic mutation siblings like save_job or apply_job. It stops short of explicitly naming which sibling to use for adjacent actions, so it is clear but not fully differentiated.

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 line 'Omit a field to leave it unchanged' gives useful partial-update guidance for the two optional fields. However, there is no statement of when to use this versus apply_job, save_job, or my_jobs, and no preconditions (e.g., whether the job must already be tracked or whether an unrouted slug creates a tracking entry).

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