Update Bookmark

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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavioral context — that unspecified fields are left untouched, making the update a merge rather than an overwrite — which is not derivable from the annotations. It omits what happens on an unknown bookmark_id, but that is a minor gap given the annotation coverage.

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 short sentences with zero padding. The mutable-field list is front-loaded, followed by the partial-update rule and then the sibling redirect — no redundant restatement of the tool name or title.

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 an output schema present, the description need not describe return values, and annotations handle the mutation/idempotency profile. Combined with 83% schema coverage, the description is sufficient for correct invocation; only edge-case behavior for invalid bookmark ids or the favourited field is left unaddressed.

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 83%, so the schema already documents most parameters, including that empty strings clear notes/summaries and restore default titles. The description adds the crucial disambiguation that a null/omitted value means 'no change' rather than 'clear', which the nullable-with-default-null schema does not spell out. The only undecorated parameter, favourited, is still implicitly defined by the description's field list.

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?

Uses a specific verb (change) plus resource (bookmark) and enumerates exactly which fields are mutable: title, note, summary, favourite, archived flag. It also pre-empts confusion with the tag siblings by naming them, so an agent can distinguish this tool from tag_bookmark/untag_bookmark and delete_bookmark without inspecting schemas.

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?

Explicitly says 'Only the fields you pass change', which tells the agent this is a partial update rather than a full replacement, and it redirects tag mutations to tag_bookmark/untag_bookmark. It does not state preconditions (e.g. that bookmark_id must reference an existing bookmark) or error behavior, so it stops short of full when/when-not guidance.

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