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

Annotations already declare readOnlyHint and destructiveHint=false, so safety is covered. The description adds real behavioral context beyond that: truncated responses are returned in line-based parts and the caller must continue with `from`, plus the tie-in to apply_timeline. Missing only detail on part size limits or format caveats.

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 dense sentences with no filler, and the identity of the returned resource is front-loaded. The header enumeration is slightly cluttered but functional.

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-shape burden, and it does describe both the header fields and the tree plus the multi-part return behavior. Only the exact part-size boundary and any diagnostics semantics remain unstated.

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 each parameter has its own description, so the baseline is 3. The description corroborates the pagination semantics of `from` ('reads on') but adds no format or constraint detail beyond what the schema already provides.

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 precisely: the canonical timeline.tsx for a project, including header components (aspect, duration, media table, diagnostics, rev) and the tree. This distinguishes it from write-side siblings, though the reading verb is only implied by the tool name rather than stated outright.

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?

Explains the pagination workflow ('a timeline longer than one result comes back in parts by line, and `from` reads on') and clarifies the relationship to apply_timeline ('takes edits copied from this text'). It gives clear usage context but no explicit exclusions versus timeline_history or check_timeline.

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