skim_open

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

With no annotations, description fully discloses behavior: returns handle, report (token counts + compression ratio), skeleton, anchors; notes collapsed bodies not in skeleton; explains query usage for matches.

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?

Concise two-paragraph description with front-loaded purpose. Every sentence adds value: purpose, return values, usage advice, collapsed bodies clarification, query optimization. No wasted words.

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?

Given 2 parameters, no output schema, and no annotations, description is highly complete: covers return values, behavior, usage, query optimization, and distinguishes from siblings.

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 coverage is 0%, but description adds meaning: path is file path, query is optional to get matches in same call. Could be more explicit but sufficient for agent understanding.

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?

Clearly states it opens a large file and returns a compact skeleton with expandable anchor ids, not full text. Distinguishes from sibling tools like skim_expand (expand anchors) and skim_search (search).

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?

Explicitly instructs to use instead of reading whole large file when only parts needed. Suggests passing query to avoid extra round-trip to skim_search. Provides clear when-to-use and when-not-to guidance.

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