Read original text around a native history anchor

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

Goes well beyond the read-only/idempotent annotations: pagination semantics ('Direct native page seek; at most five pages of maxMessages 10'), content exclusions (plugin user context, reasoning, tools, media, empty text), truncation behavior, the subtle meaning of hasEarlier ('unscanned raw prefix, not necessarily eligible text'), and a prompt-injection warning that historical text is untrusted data.

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?

Front-loaded with the action and result, and nearly every clause carries distinct information (scope, pagination, exclusions, return shape, security). It is dense and somewhat packed, but there is little genuine waste.

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 complex history-read tool it covers scope, ordering, pagination limits, exclusions, truncation, and the hasEarlier edge case, and an output schema exists so return values need not be fully re-explained. An agent has everything needed to call it correctly.

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?

With 0% schema description coverage the description must carry the load, and it does: it ties anchorSeq/throughSeq to the search result and explains maxMessageChars as the per-message character cap. It is thinner on beforeMessages (only implied by 'at most ten nearest earlier messages') and omits workspace/sessionId, so not a full 5.

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 (Read) and a precisely scoped resource: the exact user/assistant text anchor from a search result plus the nearest earlier eligible text messages. The phrase 'native history anchor' and 'from a search result' clearly distinguish it from siblings like read_session_history and search_session_history.

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 context: 'Supply the original anchorSeq and fixed throughSeq' ties invocation to a prior search result, and 'No later messages or whole conversation tree' bounds scope. It does not name an explicit alternative or state when-not to use it versus read_session_history, so it stops short of a 5.

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