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 behavior beyond that: the response shape is mode-dependent (summary + transcript excerpt for a segment vs. summary + chapters + segment ids for an episode), which an agent needs in order to plan a follow-up call.

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?

A single front-loaded sentence with the two modes clearly separated by 'or'. The parenthetical lists are dense but every element earns its place; only the missing sibling differentiation keeps it from a 5.

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 an output schema and full annotations, the description needn't explain return values, and it covers the dual-mode input adequately. The notable hole is that a sibling named get_episode exists with apparent overlap, and the description never explains the split — an agent choosing between the two has to guess.

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 100% and the schema already lists the three accepted id forms, so the baseline is 3. The description goes further by mapping each input form to its output mode (id → segment, Space id/date → episode), which is meaning the schema does not carry.

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 concrete verb (read) and two resource modes: a show segment keyed by id, and an episode keyed by Space id or date, plus the payload each returns. The generic tool name 'fetch' is rescued by this detail. What it does not do is distinguish itself from the sibling get_episode, which appears to cover overlapping territory.

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?

'id from search' and 'segment ids to fetch' sketch a two-step workflow (search, then fetch), which is genuinely useful routing. But there is no explicit statement of when to pick fetch over get_episode or search_segments, and no exclusions, so selection between the closely related siblings is left to inference.

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