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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds real value by disclosing the access-control rule ('Owners see it straight away') and the privacy nature of the payload, but says nothing about error behavior when the caller does not own a character.

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 verb and resource, with the parenthetical used efficiently to define the otherwise obscure 'afterglow' term. A single compact sentence plus a short access/alternative clause; no wasted text.

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-value burden and does so by naming both pieces of returned data (the exchanged texts and the mutual-interest verdict). Combined with the ownership precondition and the get_episode cross-reference, an agent has enough to call it correctly; only error handling is absent.

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 carries only maxLength. The description's phrase 'for an episode you own a character in' loosely implies what episode_id must reference (an episode you own), which partially compensates, but it adds no format or syntax detail beyond the schema.

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 well-defined resource (the private morning-after texts plus whether interest was mutual), scoped to 'an episode you own a character in.' It also implicitly differentiates from get_episode by noting 'get_episode carries it too,' so an agent can tell the two apart, though the overlap is described loosely.

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 a clear precondition ('an episode you own a character in') and names an alternative route ('get_episode carries it too'), so the agent knows both when it can use this and that another sibling returns the same data. It stops short of an explicit when-not or a preference rule between the two.

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