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

Annotations already establish readOnlyHint=true, destructiveHint=false, and openWorldHint=false. The description adds useful context beyond annotations: it is a legacy v1 API tool, returns exactly one session, and discloses the returned field groups. It does not discuss auth or rate limits, but that is minor given the annotation coverage.

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?

The description is two tight sentences, front-loaded with 'Legacy tool' and 'returns ONE session'. Every clause carries selection-relevant information, including the sibling contrast.

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 legacy single-record read with an output schema and rich annotations, the description is complete enough. It covers what the tool returns, why it exists, and how it differs from get_session, while the schema handles parameters and annotations cover safety.

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%, and the schema already documents session_id prefixes, container_id, and server_name. The description only reinforces that the id fetches one session and adds no syntax or constraints beyond the schema. Baseline 3 is appropriate.

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?

The description states a specific verb and resource: it returns ONE session by id from the v1 API, with named field groups. It also distinguishes the tool from sibling get_session by explaining what get_session returns but does not include. The mismatch with the name list_sessions is explicitly corrected by 'returns ONE session'.

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?

The description gives a clear contrast with sibling get_session, implying this tool should be selected when funnel-stage counts, contact flags, or the full event timeline are needed. It does not explicitly address the other session list/search/query siblings, so the guidance is strong but not exhaustive.

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