update

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

With no annotations, the description carries the full burden and does well: it discloses the mtime-based incremental mechanism, relative cost, and implicit invocation by other tools. It does not say what happens when no index exists (error vs fallback to full build) or whether the index file is mutated in place, which are the remaining behavioral gaps for a mutating refresh tool.

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 tight sentences: purpose first, then the routing decision, then the implicit-call caveat. Every sentence earns its place with zero padding.

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 mutating refresh tool with no output schema and fully documented parameters, the description covers mechanism, cost, and sibling routing. The main omission is the failure/fallback path when no prior index exists, which an agent would want before invoking it on an unindexed project.

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 schema already documents all five parameters (gpu, device, semantic, workspace, project_root) in detail. The description adds no parameter-level meaning beyond that, so the baseline 3 applies.

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 ('Incremental index refresh') plus the exact mechanism (re-parses only files whose mtime changed). It explicitly contrasts itself with the sibling `index`, so an agent can distinguish the two without opening a schema.

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?

Explicit when-to-use rule: 'Prefer over `index` when an index already exists', backed by a concrete cost comparison (<1s vs full rebuild). It also warns that most sibling tools call this implicitly via auto_update=true, which is exactly the routing context an agent needs.

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