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

Annotations already declare readOnlyHint=false, destructiveHint=true, idempotentHint=true and openWorldHint=false, so safety is partly covered. The description adds genuine context beyond them: omitted fields are left untouched, supplied text overwrites the previous value, and no starter is deleted. That 'No starter is deleted' note does not contradict destructiveHint=true, since the destructive behavior is the field-value replacement, which the description explicitly discloses.

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 compact sentence front-loads the verb and resource before the id source and the update semantics, so the key facts come first. The phrasing 'a text given replaces the old text' is slightly awkward and the closing auth note is tacked on, keeping it out of the top band.

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 5-parameter mutation tool with full schema coverage, no output schema and rich annotations, the description covers the essentials: identity of the target, partial-update semantics, non-deletion, and the account requirement. It omits error behavior for an unknown id and whether the updated starter is returned, which are minor gaps given the structured fields available.

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%, so the baseline is 3; the description earns above baseline by explaining the update contract that the per-field schema entries do not: only the fields actually supplied are changed and a supplied text replaces the old text. It doesn't add format details (e.g., the YYYY-MM-DD convention is left to 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 (change) and resource (starter), scoped to the baker's own starters, and tells the agent where the required id comes from (list_my_starters / add_starter). The clause 'only the name, birthday, notes or story given change' immediately separates it from add_starter and list_my_starters by defining the partial-update behavior.

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?

Gives a clear precondition ('by its id from list_my_starters') and an auth requirement ('Needs the baker's Loafy account'), which is enough context to invoke it correctly. It does not state when not to use it (e.g., versus add_starter for creating a new starter), so it stops short of a full when/when-not routing statement.

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