codebase_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 useful work: 'Runs synchronously' discloses blocking/latency behavior and 'Only re-indexes changed files' discloses the incremental execution model. It omits failure behavior when no index exists, permission/model requirements, and any cost/concurrency notes.

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, front-loaded with the core action and the incremental constraint, followed by the execution model and use cases. Every sentence contributes and none is redundant.

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 no-annotation, no-output-schema mutation tool, the description covers purpose, incremental scope, synchronous execution, and usage scenarios. It leaves out what the tool returns and prerequisites (e.g., whether an index must already exist), which an agent would still want.

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% for both parameters (projectPath, extraExtensions), so the schema already carries the parameter meaning and the description adds no syntax or format guidance. Baseline 3 applies when the schema does the heavy lifting.

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 precise verb+resource ('Incrementally update an existing codebase index') and immediately distinguishes its scope from a full index via 'Only re-indexes changed files.' It does not explicitly name the sibling it differs from (e.g., codebase_index), so the agent must infer the full-vs-incremental split, keeping it below a 5.

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 concrete when-to-use conditions: refresh a manual/off snapshot, catch working-tree edits before the next Git transition in git mode, or when an immediate catch-up is needed. It offers no explicit when-not-to-use or named alternative tool, so routing is clear but not fully pinned down.

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