session_get

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

Annotations already declare readOnly, idempotent, non-destructive, and open-world traits. The description adds meaningful behavioral context beyond this: a wrong id returns a teaching error rather than a traceback, which helps the agent anticipate error behavior and recovery steps.

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 compact and front-loaded: it states the operation in the first sentence, then adds the useful error-behavior and id-discovery guidance. Every sentence earns its place with no redundancy.

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 simple two-parameter read tool with a fully documented schema and no output schema, the description is complete: it explains what the tool returns conceptually, how to obtain a valid id, and what happens on failure. Nothing essential is missing for correct invocation.

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 the schema already documents both session_id and target fully. The description reinforces that session_id comes from session_list but does not add meaning beyond what the schema already provides, so the baseline of 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 operation: retrieving full detail for one Horizon session by id. It distinguishes itself from sibling list tools by emphasizing 'one session' and 'full detail', and it points to session_list for id discovery, so an agent can tell this tool apart from nearby alternatives.

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 explicitly tells the agent to use session_list to discover ids, which covers the key prerequisite and primary alternative. It also frames the tool as the correct choice when full detail for a single known session is needed, giving clear contextual guidance.

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