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

With no annotations, the description carries the burden and does meaningful work: it discloses the 409 error on an open-run mismatch, the 'clear'/late:true callback behavior when Ned has already fired, and that failed=true triggers immediate Ned firing with a 200-char error bounded message. The unexplained jargon 'Ned' and omission of any auth/permission model keep it from being fully transparent.

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?

Front-loaded with the state change and reasonably sized at four sentences, but it leans on undefined jargon ('Ned', 'clear') and packs several distinct behaviors into dense run-on clauses, reducing immediate clarity.

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, no annotations, and five parameters at 0% coverage, the description should do more. It does describe return fields and key failure modes, but omits auth/secret handling and the meaning of watch_id/run_id, leaving an agent with gaps for a multi-parameter mutation.

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 0%, so the description must compensate. It does explain error (up to 200 chars) and the semantics of failed=true, but says nothing about watch_id, signing_secret, or run_id, leaving half the parameters semantically opaque.

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 opening 'The run ended' identifies the resource (a run) and implies the completing action, and it names return fields (runtime_s, late). It stops short of an explicit verb+resource phrasing ('finish/end a run') and never contrasts itself with overrun_start, so an agent must infer the pairing.

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: 'The run ended' tells the agent it is called at the end of a run, and 'Finishing with no run open is an error (409)' gives one precondition. It names no alternative from the siblings (overrun_start, overrun_watch) nor when-not to call it.

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