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

Adds substantial context beyond the annotations: 'Opens a browser session, so it takes a while' discloses latency, and the STORED side effect (every 1:1 read is persisted, light-contact retention) explains why readOnlyHint is false despite a read operation. It also disambiguates noThread: true (ok: true, no conversation exists) from an error (lookup/read failed), which annotations cannot convey.

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 core action and structured logically (purpose → identification → latency + alternative → storage → noThread semantics → side-effect note). It is information-dense with several parentheticals, but each sentence carries distinct guidance rather than filler.

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, the description carries the return semantics itself (senderIsUs, ISO timestamps, stored row count, noThread vs error) and the safety profile (sends and changes nothing). Given four optional params and an open-world browser operation, nothing an agent needs to call it correctly is missing.

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 four parameters are already documented in the schema, including conversationUrn being 'most reliable'. The description adds only marginal routing detail (urn and/or profileUrl, profileUrl as fallback when urn omitted), so the baseline 3 for full schema coverage applies.

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 with exact scope: 'Read one thread end to end (oldest → newest)', including the return shape (senderIsUs, ISO timestamp). It distinguishes itself from the sibling li_conversation_history (stored copy) and li_read_conversations_bulk, so an agent can route without opening schemas.

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?

Explicit when-to-use and when-to-prefer-alternative: check li_conversation_history first (instant stored copy), and only call this when a live read is needed. Also names the downstream step (draft the reply, send with li_send_message) and the identification inputs (conversationUrn from li_list_conversations, and/or profileUrl).

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