cairn_read

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

No annotations are provided, so the description carries the full disclosure burden, and it does unusually well: it states the batch cap (up to 8 ids per call), the size budget semantics including the total-body cap (max(60000, this)), and the freshness guarantee that it can read just-written nodes. It does not cover failure behavior, such as what happens with an ambiguous or unknown prefix, which is the remaining gap.

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 densely packed sentences with the core action front-loaded and zero filler; every clause (follow-up role, verbatim layer, prefix matching, batch cap, budget knob, freshness) earns its 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?

With no output schema and no annotations, the description still conveys the return nature (verbatim full text, budget-controlled) and invocation constraints. It stops short of describing result ordering or error cases, which is a minor gap for such a simple two-parameter read tool.

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: 'full ids or unambiguous prefixes' clarifies how ids are matched, 'up to 8 per call' constrains the array, and max_chars is framed as dialing the per-node body budget ('raise it to pull a very long turn whole, lower it to skim').

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 ('Read specific nodes IN FULL by id') and immediately positions itself against siblings, calling itself 'the follow-up to the gists that recent/search/fetch return' and 'the verbatim layer'. An agent can tell it apart from cairn_fetch/cairn_search without opening any schema.

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 names when to use it (after getting gists from recent/search/fetch, when the full text is needed) and names the alternatives, plus a distinguishing condition: 'Unlike fetch/search this needs no embeddings, so it reads nodes written moments ago.' Selection logic is fully spelled out.

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