cairn_fetch

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

With no annotations, the description carries the full burden and largely delivers: it discloses the output shape (capped previews ~1800 chars for top hits, gists for the rest), that results are budget-fitted, and how to escalate to full text. It does not state permissions, whether the call has side effects (e.g., logging), or behavior on empty/no-match queries, so it falls short of full disclosure.

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 sentences, front-loaded with the core value proposition and the primary routing instruction. Slightly promotional phrasing ("replaces the re-reading tax") costs a bit of density, but nothing 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 3-parameter read tool with no annotations and no output schema, the description covers the essential things an agent needs: what comes back, roughly how big it is, and how to get more. Missing only edge-case behavior (no results, errors) and an explicit read-only assurance.

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 100%, so the baseline is 3, but the description adds real meaning beyond the schema: it explains that budget_tokens governs the fitted pack size and that top hits are capped at ~1800 chars while the remainder are gists. The account scoping parameter is left to the schema only.

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: one query returns a compact context pack of memories/files fitted to a token budget. It clearly contrasts with the anti-pattern (re-reading files, scrolling history) and names cairn_read for full text. It does not explicitly distinguish itself from sibling cairn_search, so the differentiation is strong but not complete.

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?

"Call this INSTEAD of re-reading files or scrolling history" gives an explicit selection condition, and "cairn_read returns any node's complete text" supplies the alternative for full fidelity. There is no explicit statement of when NOT to use it (e.g., vs cairn_search or cairn_orient), which keeps it at 4.

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