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

Annotations establish this is a non-read-only, non-idempotent, non-destructive write. The description adds a genuinely useful trait beyond them: merge semantics where 'existing keys are preserved unless explicitly overwritten.' It omits concurrency/last-write-wins behavior, which for a non-idempotent writer would be worth stating.

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, both load-bearing: the first defines the operation and its merge behavior, the second enumerates use cases. Front-loaded with the action, no filler.

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 mutation tool with full schema coverage and no output schema, the description covers what the operation does, how merging works, and why to call it. Missing only edge-case behavior like concurrent update handling, which is a minor gap.

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's 'merging new data' echoes the schema's own 'to merge into job context' for `updates` and adds nothing about `job_id` or `in_workspace`, which the schema already documents well.

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 ('Update the job context by merging new data') and clarifies the merge semantics versus replacement. It implicitly distinguishes itself from the sibling job_read_context, though it never names that sibling explicitly.

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?

It gives concrete when-to-use guidance: 'record progress, update assignment statuses, or store intermediate results.' That is clear context for invocation. It stops short of naming alternatives or exclusions (e.g., when to prefer job_read_context or job_escalate).

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