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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered structurally. The description still earns credit by disclosing filtering behavior an agent could not predict: results are tagged present/missing, and cast reference-sheet stills are silently omitted unless `all` is set — a real default that affects result interpretation.

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, no filler. The default-filter caveat is front-loaded in the second sentence where it matters most.

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-only listing tool with no output schema, the description covers what the list represents (project media with presence status) and the one non-obvious default. Return shape beyond the present/missing marker is left implicit, which keeps it short of a 5.

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%, so baseline is 3. The description adds meaning beyond the schema by stating the default state of `all` (stills are left out unless set), which the schema's 'Include cast reference-sheet stills' does not make explicit.

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 the resource (media in a project) and adds a distinguishing detail — each entry is marked present or missing — which separates it from write-side siblings like add_media or probe_media. It's phrased as a noun fragment rather than an explicit verb, and no sibling is named, so it stops short of a 5.

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?

Usage is implied by the description rather than stated: it clarifies that cast reference-sheet stills are excluded by default and that `all` opts them back in. There is no explicit when-to-use-this-vs-another-tool guidance against the many search_*/probe_media siblings.

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