Prepare Compact Local Context

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

Annotations already establish readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavior beyond that: it relies on a persistent local index (which may be stale) and explicitly warns that cited file:line evidence should be verified, indicating the output is not authoritative on its own.

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, no filler. The core function is front-loaded, and the usage guidance and verification caveat are each one clause, earning their place.

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?

The description covers what the tool does and when to prefer it, but with no output schema and five underdocumented parameters, an agent still lacks a clear picture of the returned 'context capsule' structure and how to fine-tune it. It is adequate for a high-level selection decision but not fully complete for confident invocation.

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%, so the description carries the burden of explaining parameters. It only implies size limits through the word 'compact' and does not clarify the semantics of 'hints', 'maxFiles', 'maxCharsPerFile', or how 'workspace' and 'task' interact with the index. This leaves significant ambiguity for an agent selecting parameter values.

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 uses a specific verb ('Build') and describes a concrete resource ('compact evidence-first context capsule') plus the mechanism ('persistent local repository index'). It clearly separates this tool from the execute/search/delegate siblings by framing its output as context preparation rather than task execution or discovery.

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 description explicitly says to prefer this tool before broad Claude file exploration, and to use it for architectural or risky decisions where file:line evidence must be verified. It provides clear context and timing, though it does not name specific sibling tools or state explicit exclusions.

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