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

Beyond readOnlyHint=false and destructiveHint=true, the description discloses partial-update semantics ('only provided fields are changed — omitted fields remain unchanged'), immediate effect, replace-vs-merge behavior for tags/metadata, the shortUrlDTO return value, and the exact READ_ONLY-mode failure ('returns an operation_not_permitted error immediately without making any API call'). This materially exceeds what annotations alone convey. No contradiction with the annotations.

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?

Purpose is front-loaded in the first sentence, followed by one distinct fact per sentence: partial update, immediacy, id sourcing, supported fields, return type, mode gating. The field enumeration is partly redundant with the schema but earns its place as a single-summary of update behavior.

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 present, the description closes the return-value gap by stating 'Returns the updated ShortUrlDTO.' It also covers the READ_ONLY failure path, destructive semantics, and per-field change behavior for a 7-parameter mutation with nested objects — little is left for the agent to infer.

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 every parameter is already documented with behavior ('pass null to remove an existing expiration', 'replaces — not merges — the existing tags'). The description repeats these same semantics rather than adding new meaning, which is the baseline-3 case for high coverage.

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 and resource: 'Update an existing short URL's configuration.' The scoped field list ('title, expiresAt, isActive, tags, metadata, longUrl') plus the sequencing note 'Use after nevent_list_short_urls' clearly distinguishes it from the create/get siblings (nevent_create_short_url, nevent_get_short_url). No ambiguity remains about what this tool does.

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 tells the agent when to call it: 'Use after nevent_list_short_urls to get the id.' The WRITE-operation / READ_ONLY-mode warnings also tell the agent when the call will fail. It never names an explicit exclusion (e.g., 'use nevent_create_short_url to create instead'), but for a single-purpose mutation the sequencing guidance supplies enough context.

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