build_digest

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safe-read profile is covered. The description adds real behavioral value by warning that excerpts are only the beginning of files (do not claim to have read the full document) and by instructing disclosure when the 'truncated' flag is True. No contradiction with annotations.

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?

The description is front-loaded with the primary purpose, and the critical operational warnings are emphasized with bold. Every sentence earns its place; the length is justified by the behavioral caveats. Slightly verbose but well-structured for the information density required.

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?

An output schema exists, so return format is covered. The description covers purpose, usage timing, the excerpt-limitation caveat, and the truncated behavior. It does not mention what file types are excluded beyond the ext filter, but given the output schema and rich behavior notes, this is largely complete.

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 all three parameters (ext, limit_files, chars_per_file) are already documented with defaults and ranges. The description adds no extra parameter semantics beyond the schema, which is the expected baseline when the schema carries the full load.

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 purpose: 'collects materials for summarizing an entire folder at once' and defines the exact output shape (condensed structure + beginning of body per file). It distinguishes itself from extract_content by scope (batch folder operation vs. per-file deep reads) and names the use case 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?

Gives clear when-to-use guidance: call this first for requests like 'summarize this whole folder' to reduce round trips. It also routes to extract_content for files that affect conclusions. It stops short of explicitly stating when NOT to use it (e.g., single-document queries), so the exclusion guidance is implied rather than spelled out.

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