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

With no annotations provided, the description carries the full burden, and it delivers: it discloses that the tool writes exactly one stop, returns the current stop count, touches the network over TLS, treats the #k= phrase as a password/credential, stores nothing about the user, and counts a wrong phrase as a guess. This goes far beyond what the schema or annotations could convey and is critical for an agent handling a credential-bearing link.

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?

The description is dense but every sentence earns its place: intent examples, credential warning, network behavior, and a pointer to the sibling tool. It front-loads the core action and the critical credential requirement before the security context. No fluff or repetition of schema details.

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 2-parameter tool with a nested object and no output schema, the description covers the essential context: when to use it, the credential requirement, the network/security implications, the single-write behavior, and the return value (current stop count). The only thing an agent might want is the exact response shape, but the description already states the stop count, and the schema covers the parameters. This is complete for safe and correct invocation.

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%, so the baseline is 3, but the description adds meaningful context: it clarifies that the link must contain the #k= EDIT phrase (not just any link), and that the stop object is the thing being written. It also references read_kept_trip for the track field's naming. The only minor gap is that it doesn't explain the lat/lng format, but the schema already describes the fields, so this is above baseline.

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?

The description opens with a specific verb and resource ('Add a stop to a trip the person has KEPT'), and immediately distinguishes this from read-only siblings by naming the credential requirement. It also gives concrete example phrasings ('add X to the trip', 'we're stopping at Y on the way') that an agent can match against user intent. This is clearly differentiated from read_kept_trip and read_trip_link.

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?

The description explicitly states when to use it ('Use when they say...') and provides the key exclusion: a view phrase can read but not write, so this tool requires the EDIT phrase. It also names the sibling read_kept_trip as the source for the track parameter and for reading the trip, which routes the agent correctly. This is exemplary usage guidance.

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