update_cover

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

With no annotations, the description carries the full burden; it does usefully disclose the mutation target file (cover/config.yml) and the side effect that a local image can be copied into cover/. However, it omits critical mutation semantics: whether omitted fields retain existing values or fall back to the schema defaults, and whether logo_source_path overwrites an existing logo file.

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 dense sentence that front-loads the target file and then enumerates the modifiable areas, ending with the optional image side effect. No filler or repetition.

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 no-output-schema mutation tool with nested objects, the description covers the modifiable surface and the one non-obvious side effect. Remaining gaps (merge-vs-default behavior, overwrite semantics, post-update regeneration) are real but modest given the fully documented schema.

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% with per-property descriptions for the nested header/footer/logo objects, so the schema does the heavy lifting. The description confirms the field groups and hints at the image-copy behavior of logo_source_path but adds no format, constraint, or interaction details 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 ('Updates') plus the exact resource ('cover/config.yml') and enumerates the settings groups touched (header titles/padding, logo size/image name, footer title/size). The read/write split against the sibling get_cover is self-evident from the names, though the description never names that sibling explicitly.

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 only implied: an agent can infer this is the tool for changing existing cover configuration versus init_songbook for setup. There is no statement of prerequisites (e.g., an existing songbook project, whether generate_songbook must be re-run afterwards) and no when-not guidance.

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