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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the bar is lower; the description still adds real value by disclosing the permission scoping ("the signed-in user can reach") and the return shape ("short summaries," full record via get-shoot-day). It omits ordering and pagination behavior, which the schema partly covers via page/per_page.

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?

Three sentences, front-loaded with purpose, then return shape, then filtering options. Nothing is redundant and every sentence carries a distinct decision-relevant fact.

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 read-only, closed-world list tool with a fully documented 6-parameter schema and no output schema, the description covers purpose, scope, return granularity, and the escalation path to get-shoot-day. Only ordering/pagination expectations are unstated, a minor gap given the schema's page/per_page docs.

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 parameter descriptions already explain page, per_page, script, project, project_id, and search. The description's "narrowed to one project, or to the days filming a particular script, by name" restates the schema rather than adding new semantics, so the baseline 3 applies.

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?

"List the days of filming the signed-in user can reach, with their dates and what each one is for" names a specific verb (list), the resource (shoot days), the scope (user-accessible), and the returned fields. It is immediately distinguishable from get-shoot-day and create-shoot-day in the sibling list.

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 explicitly routes the agent to the alternative: "call get-shoot-day for one in full," which tells the agent when this tool is insufficient. It also states the two narrowing modes (project, script). It does not address when to prefer this over the generic `search` sibling, so it stops just short of a full when/when-not map.

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