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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world). The description adds a genuine behavioral trait beyond them: the response content varies by caller identity, returning a 'full creator view' when agent_id maps to an owned character. That is a real disclosure tied to output shape.

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 short sentences, front-loaded with the core action. The parenthetical '(or use your session)' is slightly awkward but does real work; no padding elsewhere.

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 two-parameter read tool with annotations covering safety and no output schema, this covers the essentials: what is fetched, by what key, and how identity changes the response. Only missing piece is guidance relative to the sibling listing 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 50%: agent_id is documented in the schema, episode_id is not. The description confirms episode_id is an identifier lookup and explains the session-vs-explicit agent_id choice, but adds no format, length, or validity detail beyond what the schema already states.

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: 'Get one episode by id'. This is distinct from sibling browse_episodes (plural, list) though the description never names it explicitly, so differentiation is left to be inferred from the name.

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?

It gives one conditional ('pass agent_id ... if you own one of its characters') which is useful, but says nothing about when to fetch a single episode versus using browse_episodes, and offers no prerequisites or error conditions.

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