Merge PDFs

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

Annotations cover the safety profile (readOnlyHint=false, openWorldHint=true, destructiveHint=false, idempotentHint=false), so the bar is lower. The description still adds meaningful disclosure: files are uploaded to an external service (conv2pdf), the call is metered as one conversion, and the result lands next to the first file. Nothing contradicts 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?

Four short sentences, front-loaded with what the tool does, then cost/limit context. Every sentence carries information, though the 'written next to the first file' clause lightly duplicates the output_path default in the schema.

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 two-param tool with no output schema, the description covers destructive behavior (no overwrite), external upload, quota cost, and plan-dependent item limits — enough for an agent to call it correctly. It omits failure modes and any auth requirements for the conv2pdf upload, which are minor gaps.

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% and both parameters (input_paths with min/maxItems, output_path with defaults and no-overwrite behavior) are already fully documented. The description only restates ordering and default placement, adding no syntax or format detail beyond the schema. Baseline 3 applies.

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 ('Combines several PDFs into one') plus the ordering semantics, which no sibling does — every sibling tool (convert_*, rotate_pdf, compress_pdf, etc.) operates on a single file. An agent can distinguish this from the rest of the list without opening any schema.

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 operational context that shapes use: a 2-file minimum on the Dev plan, up to 20 on paid plans, and that the call consumes one conversion from quota. It does not explicitly name when to prefer an alternative, but the resource is unique among siblings so no real disambiguation is required.

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